Computer Pin Out for A9L

[AnthonyR23]

It's been awhile since I have posted on here, it has been a few years since I put a new 347 rebuild in my car and haven't had it running right ever since, I changed so many things including mass air conversion, so it is difficult to narrow down what the problem is, I have had it running at points, tried changing some settings with moates quarterhorse, but my a/f ratio with wideband innovate kit is all over the place, at idle it has been anywhere from 10.1 up to 21. a/f ratio and usually at that point I shut it down because I am afraid I will do damage if it is running that lean. I can't get it idle right either. So what I was thinking since I have been running around in circles for years that before I turn it into a tuning shop I should verify the wiring from when I did my mass air conversion. If someone could direct me to the mass air conversion instruction sheet I could check that the pins to the mass air meter for continuity. Any other idea's would be great. What I have..

347 Probe industries bottom end kit
Trick Flow Street Heads and Intake
2030 Crane Cam
accufab 75mm tb with 4 inch opening
4 inch anderson powerpipe
93mm velocity mass air meter calibrated for 30lb injectors
30lb injectors with new rails and fuel pressure regular
larger fuel pump
3g alternator
mass air conversion with pigtail, and a9l from ebay.
underdrive pulleys
air conditioning removed
larger 3 core rad with electric fan
equal length headers, 2.5 inch x pipe including cats with 2.5 inch borla catback
subframe connectors
still running egr valve and smog pump
new vacuum lines
new msd ignition box, distributor and coil
high torque mini starter
3g alternator
new battery
battery moved to trunk
billet alluminum flywheel
deep sump oil pan new oil pump and water pump
moates quarterhorse software with innovate wideband

I am pretty close to giving up and taking it into misener motorsports and having them do a chip and dyno tune, I am just afraid of getting a crazy bill for troubleshooting, so would like to have the car as solid before bringing it in. So frustrating, but can admit I need some help. Just thinking if I could verify some of the new wiring from the mass air conversion I may be headed in the right direction. Oh and I need emissions here in Ontario that is why I left on the smog and egr and why I am running with cat's. But think if I get it properly tuned I may be alright. Thanks

 

[90stang5speed]

A Haynes manual has the EEC schematic in it. Mine is a 90 and a A9P but Im pretty sure there is a schematic in there for the A9L also. as for the tune, I would down load a stock A9L tune from the EEC analyzer site to compare to your tune. I just put 42 lb injectors in mine & what I read on the tuner forum was to divide 19 by your new injector size and the multiply the tables like bat offset & start up fuel table by the % you get. I will try to post more later. Im at work right now

 

[FobraR]

Try this link, lots of great info on the site. Ford Fuel Injection » Wiring Harnesses

 

[liljoe07]

Mustang FAQ - Wiring, Engine, Air Bag, ABS Home Page


All MAF foxbody 5.0 ECMs have the same PIN out at the 60 PIN connector.

 

[90stang5speed]

I did some more searching & what I found was. Lets say you were to download an A9L Bin. Then input your current injector size as the high slope, make the low slope about 15% larger. Input your eng cubic inches. divide 19(stock injector size) by 30 (new injector size) that = .63 multiply cranking pulse with VS ECT by .63. & multiply Injector offset VS bat voltage by .63. That should be able to get you started & be able idle. from there you can make adjustments to other parts of the tune. Im no pro at this stuff but, I have learned that when I change a lot of stuff in the tune & it runs like crap, the best thing for me to do is back up & start fresh if I cant remember what I changed. I hope that helps but, like I said Im not a pro tuner.

 

[AnthonyR23]

Okay.. I will try that.. I feel like I have rechecked everything a hundred times and tried to mechanically adjust what I could.. I will download the stock a9l, I think I have the original copy but will download it just in case.. will try over the weekend.. It's very frustrating because I have checked timing, and idle screw position and tps sensor. Have tried changing tuning settings, watching the a/f ratio, while I make changes.. Is there a range that I should shut down engine if I am outside of.. like at startup, what is normal for A/F ratio and at what point should I shut it down to avoid damage.. like if I see 20.. to avoid damage should I shut it down.. maybe I am too nervous and not giving tuning adjustments a chance, but when I have tried and have seen too high of a a/f, I have shut it down.

 

[f8tlfiveo]

Go to eectuning.org talk to decipha (screen name) he will tune your car over the phone for 100$.he is just finishing my car right now.. He is very knowledgeable with this stuff. You might not get every last pony out of the car without dyno tuning but that would cost you a lot more. Datalogs are great for tuning over the phone and Internet.

 

[90stang5speed]

Mine was idling at full lean(22) and didnt do any damage. At very low load at idle you shouldnt have to worry too much. Is there any chance you still have the stock MAF & injectors laying around? If so, you could put them back in just to get a base tune going. I think the throttle screw is supposed to be set at around 550-600 RPM with the SPOUT unplugged & the IAC unplugged. It should just barely be able to run. If not, The MAF you have is calibrated to the bigger injectors so, you may not need to do that anyway. You can also just do a read from the ECC with your tuner to get the stock BIN. You might want to disconect the bat & hold the brake pedal for a few seconds to clear out the KAM data that might be messing with your tune a little until you can get a good base. Im still tuning in open loop so that the EEC wont try to learn on its own while Im making mistakes lol. I have emailed back and forth with Decipha also & he as well as others on that site are very helpfull. I wasnt asked to pay anyone for their advice but I didnt get a full tune from them either. Good luck with your tuning

 

[AnthonyR23]

Okay thanks guys, I will let you guys know how it goes tomorrow. I will get it out in the day and see what I can do.

 

[2000xp8]

Definetely get the car running right before you even consider taking it to a shop.
If you want to play with a tuner that's fine, but before you mess with a single thing in tuning, make sure the car runs right.
Once you alter something in the tune to fix a problem that shouldn't exist, you make trouble shooting even harder.

There is nothing in your setup all that intricate. With no tune at all your car should run and idle as well as a stock setup.
If you take it to a shop running wrong before you know it you will owe then $1500 for fixing things you didn't even know were wrong.

I've seen it so many times at my buddies shop, people show up with tuners and think miracles are going to happen.

If that combo needs a tuner to run you did in fact mess us the mass air conversion or you have some type of mechanical malfunction.

 

[AnthonyR23]

Okay, so I put the original A9L factory tune in but changed engine displacement - 347, and cranking pulse vs ect and injector offset vs battery voltage. By .63. Only thing I want to make sure of is that I am multiplying the right side by .63. For cranking Pulse vs ect there is a DegF and mSec. I multiplied the mSec side by .63 and left DegF the same.. Is that right? and same for injector offset vs battery voltage I multiplied the mSec side and left Voltage the same. Is this right??

Okay so after this I tried starting it up.. it did fire right up again but then quit like wouldn't idle.. Just want to make sure for future changes that I am doing the right thing above.. but I am also taking the advice and backing right up. I re wrote the base A9L.

So I thought a good place to start would be to check the engine off codes again, which I think I did last year but it seems different. I did just have the battery out but through it back in and these are the engine off codes I got.

15 21 24 81 82 and 96

 

[AnthonyR23]

15 PCM Read Only Memory (ROM) teat failed.
21 ECT out of Self-Test range MAP/BARO out of Self-Test range.
24 IAT out of Self-Test range.
81 Secondary -Air Injection Diverter (AIRD) solenoid circuit failure.
82 Secondary Air Injection Bypass (AIRS) solenoid circuit failure.
96 ???

 

[AnthonyR23]

ooops didn't put the original a9l on, still had the a9l with the first three changes posted above.. when I put the original one on.. lost some codes.. here is what I have with the original a9l bin.

21 24 81 82 and 96

 

[jrichker]

15 PCM Read Only Memory (ROM) teat failed.
21 ECT out of Self-Test range MAP/BARO out of Self-Test range.
24 IAT out of Self-Test range.
81 Secondary -Air Injection Diverter (AIRD) solenoid circuit failure.
82 Secondary Air Injection Bypass (AIRS) solenoid circuit failure.
96 ???

Code 15 - No Keep Alive Memory power to PCM pin 1 or bad PCM (Memory Test
Failure). The voltage to the Keep Alive Memory (KAM) is missing (wiring problem)
or the KAM is bad. The KAM holds all of the settings that the computer "learns" as
it operates and all the stored error codes that are generated as a result of
something malfunctioning while the engine is running. Use a voltmeter to check
the voltage to the pin 1 on the computer - you should always have 12 volts. No
constant 12 volts = bad wiring. If you do always have the 12 volts, then the KAM is
bad and the computer is faulty.

If the computer has to "relearn" all the optimum settings every time it powers up,
the initial 5-30 minutes of operation may exhibit surges, poor low speed performance,
and rough idle.

Note that some aftermarket chips will cause code 15 to set. Remove the chip,
clear the codes and retest.

Before replacing the computer, remove the battery ground cable for about 20
minutes. This will clear all the codes. Retest after several days of running. If the 15
code is gone, then don't worry about it. If it is still there, then you get to do some
troubleshooting.

See the following website for some help from Tmoss (diagram designer) & Stang&2
Birds (website host) for help on 88-95 wiring Mustang FAQ - Wiring & Engine Info

Diagram courtesy of Tmoss & Stang&2birds

Code 21 – ECT sensor out of range. Broken or damaged wiring, bad ECT sensor.
Note that that if the outside air temp is below 50 degrees F that the test for the ECT can be in error. Warm the engine up until you get good hot air from the heater and then dump the codes again.

The ECT sensor has absolutely nothing to do with the temperature gauge. They are different animals. The ECT sensor is normally located it the RH front of the engine in the water feed tubes for the heater.

The ACT & ECT have the same thermistor, so the table values are the same

ACT & ECT test data:

Use Pin 46 on the computer for ground for both ECT & ACT to get most accurate readings.

Pin 7 on the computer - ECT signal in. at 176 degrees F it should be .80 volts

Pin 25 on the computer - ACT signal in. at 50 degrees F it should be 3.5 volts. It is a good number if the ACT is mounted in the inlet airbox. If it is mounted in the lower intake manifold, the voltage readings will be lower because of the heat transfer.

Voltages may be measured across the ECT/ACT by probing the connector from the rear. A pair of safety pins may be helpful in doing this. Use care in doing it so that you don't damage the wiring or connector.

Here's the table :

50 degrees F = 3.52 v
68 degrees F = 3.02 v
86 degrees F = 2.62 v
104 degrees F = 2.16 v
122 degrees F = 1.72 v
140 degrees F = 1.35 v
158 degrees F = 1.04 v
176 degrees F = .80 v
194 degrees F = .61
212 degrees F = .47 v
230 degrees F = .36 v
248 degrees F = .28 v

Ohms measures at the computer with the computer disconnected, or at the sensor with the sensor disconnected.

50 degrees F = 58.75 K ohms
68 degrees F = 37.30 K ohms
86 degrees F = 27.27 K ohms
104 degrees F = 16.15 K ohms
122 degrees F = 10.97 K ohms
140 degrees F = 7.60 K ohms
158 degrees F = 5.37 K ohms
176 degrees F = 3.84 K ohms
194 degrees F = 2.80 K ohms
212 degrees F = 2.07 K ohms
230 degrees F = 1.55 K ohms
248 degrees F = 1.18 k ohms

Diagram courtesy of Tmoss & Stang&2birds

Code 24 - Intake Air Temperature (ACT) sensor out of range.
Bad sensor, bad wiring. The ACT for Mustangs built before 95 is in the
#5 intake runner. It measures the air temperature in the intake to help
computer the proper air/fuel ratio.

Note that that if the outside air temp is below 50 degrees F that the test for the ACT can be in error.

ACT & ECT test data:

The ACT & ECT have the same thermistor, so the table values are the same

Pin 7 on the computer - ECT signal in. at 176 degrees F it should be .80 volts

Pin 25 on the computer - ACT signal in. at 50 degrees F it should be 3.5 volts.
It is a good number if the ACT is mounted in the inlet airbox. If it is mounted in
the lower intake manifold, the voltage readings will be lower because of the heat transfer.
Here's the table :

50 degrees F = 3.52 v
68 degrees F = 3.02 v
86 degrees F = 2.62 v
104 degrees F = 2.16 v
122 degrees F = 1.72 v
140 degrees F = 1.35 v
158 degrees F = 1.04 v
176 degrees F = .80 v
194 degrees F = .61
212 degrees F = .47 v
230 degrees F = .36 v
248 degrees F = .28 v

Ohms measures at the computer with the computer disconnected,
or at the sensor with the sensor disconnected.

50 degrees F = 58.75 K ohms
68 degrees F = 37.30 K ohms
86 degrees F = 27.27 K ohms
104 degrees F = 16.15 K ohms
122 degrees F = 10.97 K ohms
140 degrees F = 7.60 K ohms
158 degrees F = 5.37 K ohms
176 degrees F = 3.84 K ohms
194 degrees F = 2.80 K ohms
212 degrees F = 2.07 K ohms
230 degrees F = 1.55 K ohms
248 degrees F = 1.18 k ohms


Code 81 – Secondary Air Injection Diverter Solenoid failure AM2. The solenoid valve located on the back side of the passenger side wheel well is not functional. Possible bad wiring, bad connections, missing or defective solenoid valve. Check the solenoid valve for +12 volts at the Red wire and look for the Lt Green/Black wire to switch from +12 volts to 1 volt or less. The computer controls the valve by providing a ground path on the LT Green/Black wire for the solenoid valve.

With the with the ignition on, look for 12 volts on the red wire on the solenoid connector. No 12 volts and you have wiring problems.

With the engine running, stick a safety pin in the LT Green/Black wire for the solenoid valve & ground it. That should turn the solenoid on and cause air to flow out the port that goes to the pipe connected to the cats. If it doesn't, the valve is bad. If it does cause the airflow to switch, the computer or wiring going to the computer is not signaling the solenoid valve to open.

Putting the computer into self test mode will cause the solenoid valve to toggle. If you listen carefully, you may hear it change states.


Code 82 – Secondary Air Injection Diverter Solenoid failure AM1. Possible bad wiring, bad connections, missing or defective solenoid valve. Check the solenoid valve for +12 volts at the Red wire and look for the Red/White wire to switch from +12 volts to 1 volt or less. The computer controls the valve by providing a ground path on the Red/White wire for the solenoid valve

With the engine running, stick a safety pin in the Red/White wire for the solenoid valve & ground it. That should turn the solenoid on and cause air to flow out the port that goes to the pipe connected to the heads. If it doesn't, the valve is bad. If it does cause the airflow to switch, the computer or wiring going to the computer is not signaling the solenoid valve to open.

Both 81 & 82 codes usually mean that some uneducated person removed the solenoid control valves for the Thermactor Air system in an attempt to make the car faster. It doesn't work that way: no working control valves can cause the cat converters to choke and clog.


Code 82 – Secondary Air Injection Diverter Solenoid failure AM1. Possible bad wiring, bad connections, missing or defective solenoid valve. Check the solenoid valve for +12 volts at the Red wire and look for the Red/White wire to switch from +12 volts to 1 volt or less. The computer controls the valve by providing a ground path on the Red/White wire for the solenoid valve

With the engine running, stick a safety pin in the Red/White wire for the solenoid valve & ground it. That should turn the solenoid on and cause air to flow out the port that goes to the pipe connected to the heads. If it doesn't, the valve is bad. If it does cause the airflow to switch, the computer or wiring going to the computer is not signaling the solenoid valve to open.

Both 81 & 82 codes usually mean that some uneducated person removed the solenoid control valves for the Thermactor Air system in an attempt to make the car faster. It doesn't work that way: no working control valves can cause the cat converters to choke and clog.



Since I missed seeing what year car you have, I have posted both code test paths for 87-90 & 91-93 5.0 Mustangs.

Code 96 – KOEO- Fuel pump monitor circuit shows no power - Fuel pump relay or battery power feed was open - Power / Fuel Pump Circuits. The fuel pump lost power at some time while the ignition switch was in the run position.

Look for a failing fuel pump relay, bad connections or broken wiring. The fuel pump relay is located under the Mass Air Meter on Fox bodied stangs built after 91. On earlier model cars is under the passenger seat. On Mass Air Conversions, the signal lead that tells the computer that the fuel pump has power may not have been wired correctly. See Mustang Mass Air Conversion «

Look for power at the fuel pump - the fuel pump has a connector at the rear of the car with a pink/black wire and a black wire that goes to the fuel pump. The pink/black wire should be hot when the test connector is jumpered to the test position. . To trick the fuel pump into running, find the ECC test connector and jump the connector in the lower RH corner to ground.

87-90 Models:
Using the diagram, check the red/black wire from the fuel pump relay: you should see 12 volts or so. If not, check the inertia switch: on a hatch it is on the drivers side by the taillight. Look for a black rubber plug that pops out: if you don't find it, then loosen up the plastic trim. Check for voltage on both sides of the switch. If there is voltage on both sides, then check the Pink/black wire on the fuel pump relay: it is the power feed to the fuel pump. Good voltage there, then the fuel pump is the likely culprit since it is getting power. No voltage there, check the Orange/Lt blue wire, it is the power feed to the fuel pump relay & has a fuse link in it. Good voltage there & at the Pink/black wire, swap the relay.

Code 96 causes & tests 91-93 models. – KOEO- Fuel pump monitor circuit shows no power - Fuel pump relay or battery power feed was open - Power / Fuel Pump Circuits. The fuel pump circuit lost power at one time or another.

Look for a failing fuel pump relay, bad connections or broken wiring. The fuel pump relay is located under the Mass Air Meter on Fox bodied stangs built after 91. On earlier model cars is under the passenger seat. On Mass Air Conversions, the signal lead that tells the computer that the fuel pump has power may not have been wired correctly. See Mustang Mass Air Conversion | StangNet

Diagram of the fuel pump wiring for 91-93 cars.

Look for power at the fuel pump - the fuel pump has a connector at the rear of the car with a pink/black wire and a black wire that goes to the fuel pump. The pink/black wire should be hot when the test connector is jumpered to the test position. To trick the fuel pump into running, find the ECC test connector and jump the connector in the lower RH corner to ground. No voltage when jumpered, check the fuel pump relay and fuse links.

Power feed: Look for 12 volts at the pink/black wire (power source for fuel pump relay). No voltage or low voltage, bad fuse link, bad wiring, or connections. Remember that on 92 or later models the fuel pump relay is located under the Mass Air meter. Watch out for the WOT A/C control relay on these cars, as it is located in the same place and can easily be mistaken for the fuel pump relay.

Relay: Turn on the key and jumper the ECC test connector as previously described. Look for 12 volts at the dark green\yellow wire (relay controlled power for the fuel pump). No voltage there means that the relay has failed, or there is a broken wire in the relay control circuit.

91-93 Models:
Using the diagram, check the dark green/yellow wire from the fuel pump relay: you should see 12 volts or so. If not the relay has failed or is intermittent. Check the inertia switch: on a hatch it is on the drivers side by the taillight. Look for a black rubber plug that pops out: if you don't find it, then loosen up the plastic trim. Check for voltage on both sides of the switch. If there is voltage on both sides, then check the Pink/black wire on the fuel pump relay: it is the power feed to the fuel pump. Good voltage there, then the fuel pump is the likely culprit since it is getting power. No voltage there, check the Pink/black wire, it is the power feed to the fuel pump relay & has a fuse link in it. Good voltage there & at the dark green/yellow wire, swap the relay.



See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring http://www.veryuseful.com/mustang/tech/engine/ Everyone should bookmark this site.

Ignition switch wiring
http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

Fuel, alternator, A/C and ignition wiring
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

Vacuum diagram 89-93 Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg

HVAC vacuum diagram
http://www.veryuseful.com/mustang/tech/engine/images/Mustang_AC_heat_vacuum_controls.gif

TFI module differences & pinout
http://www.veryuseful.com/mustang/tech/engine/images/TFI_5.0_comparison.gif

Fuse box layout
http://www.veryuseful.com/mustang/tech/engine/images/MustangFuseBox.gif

 

[AnthonyR23]

New Results

Hi, I have long way to go but have made some progress taking steps backwards.. with the base tune, after checking codes, I reset my idle screw to 1.5 turns and checked my tps voltage. with the engine running I can back the screw to 1 turn which will keep it running with iac unplugged down to .5 turns it stalls. Then if I go back up to 1 and try to start with iac plugged back in it won't keep running so seems like 1.5 turns is a sweet spot because it will fire up and idle fairly smoothly at about 950 rpm. At initially start up it ran at about 14.5 to 1 a/f, then once up to temp. it idled around 19 to 21 a/f which seems high. But idle felt smooth. No surging. I was happy to cause just installed a new 3 core rad with fan and since install haven't had it up to operating temp to see if fan fires up but it did, I do have to hook it up to an ignition source because after I shut off the car it still runs, just hooked it up temp. to a 12 v constant so have to fix that but no big deal. I am going to recheck my fuel pressure and set it at base with vacuum unplugged and will recheck that I have advance at 10 degrees with spout unplugged for a base. But I am excited for now to have made a little progress.. After it ran and got up to operating temp.. I shut it down, checked engine off codes and got...

81 82 and 96.

As I recall with my 88 gt vert, when I did the mass air conversion I am pretty sure it is normal to get the 96 code for fuel pump circuit. But I am going to follow jrich's instructions and investigate the solenoids for code 81 and 82. I did replace them in the last few years so will have to check wiring as I think something changed with it when I did the conversion... So I think I can fix that one.

After this I checked oil and coolant just to be sure and I'm still all good there!

Did a engine running test and jotted down what I could 8 8 66 98 66 could have messed it up and will try again to be sure what codes I got..

Anyways gonna keep playing..

 

[AnthonyR23]

Think I'm out of gas!

 

[AnthonyR23]

Troubleshooting code 81 and 82. I am getting 12 volts to both red wires.

 

[AnthonyR23]

checked continuity of pin 32 and pin 38 to the green wire and the white/red wire from the solenoids with a battery test light to the harness at computer. Had to take out that 10mm bolt and unhook computer to make sure I moved wires to 32 and 38 and they are both wired right. So now just unhooking one solenoid at a time and trying to see if we can put power and ground to it to see if they open/close...

 

[jrichker]

Troubleshooting code 81 and 82. I am getting 12 volts to both red wires.

That is supposed to be like that. The computer provides a ground to activate the solenoids. If it is a Mass air conversion of a speed density harness, there are some pins that may have not gotten moved correctly. The 32 & 38 pins are for the thermactor air solenoids you are working with.

See Mustang Mass Air Conversion « for more help.

The code 66 concerns me, since it is a MAF trouble code.

Code 66 MAF below minimum test voltage.
Insufficient or no voltage from MAF. Dirty MAF element, bad MAF, bad MAF wiring, missing power to MAF. Check for missing +12 volts on this circuit. Check the two links for a wiring diagram to help you find the red wire for computer power relay switched +12 volts. Check for 12 volts between the red and black wires on the MAF heater (usually pins A & B). while the connector is plugged into the MAF. This may require the use of a couple of safety pins to probe the MAF connector from the back side of it.

There are three parts in a MAF: the heater, the sensor element and the amplifier. The heater heats the MAF sensor element causing the resistance to increase. The amplifier buffers the MAF output signal and has a resistor that is laser trimmed to provide an output range compatible with the computer's load tables.

The MAF element is secured by 2 screws & has 1 wiring connector. To clean the element, remove it from the MAF housing and spray it down with electronic parts cleaner or non-inflammable brake parts cleaner (same stuff in a bigger can and cheaper too).

Changes in RPM causes the airflow to increase or decease, changing the voltage output.. The increase of air across the MAF sensor element causes it to cool, allowing more voltage to pass and telling the computer to increase the fuel flow. A decrease in airflow causes the MAF sensor element to get warmer, decreasing the voltage and reducing the fuel flow. Measure the MAF output at pins C & D on the MAF connector (dark blue/orange and tan/light blue) or at pins 50 & 9 on the computer. Be sure to measure the sensor output by measuring across the pins and not between the pins and ground.

At idle = approximately .6 volt
20 MPH = approximately 1.10 volt
40 MPH = approximately 1.70 volt
60 MPH = approximately 2.10 volt

Check the resistance of the MAF signal wiring. Pin D on the MAF and pin 50 on the computer (dark blue/orange wire) should be less than 2 ohms. Pin C on the MAF and pin 9 on the computer (tan/light blue wire) should be less than 2 ohms.

There should be a minimum of 10K ohms between either pin C or D on the MAF wiring connector and ground. Make your measurement with the MAF disconnected from the wiring harness.


See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring Mustang FAQ - Wiring & Engine Info

Ignition switch wiring
http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

Fuel pump, alternator, ignition & A/C wiring
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

Computer,. actuator & sensor wiring
http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

Fuse panel layout
http://www.veryuseful.com/mustang/tech/engine/images/MustangFuseBox.gif

Vacuum routing
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg

Code 98 - basic computer internal tests not passed before it started processing the request to dump codes. Do a Key On Engine Off test before starting the engine. Wait until you see the 11 flash before pressing any buttons if you have a hand operated scanner. The computer is operating in Limp mode, so fix any codes it dumps prior to doing anything else.

 

[AnthonyR23]

For code 81 and 82 I checked both solenoids and they are both functional.. sucking vaccum through the bottom, when grounded it blocks the air from going through for both, and the wiring to the comp is continuous, and both are getting 12v.. Going to try engine off test again. Anything else I can check? for 81 and 82?