Can't get TPS voltage above .15 volts - part 2

tps

90topdown said:

Update-

JOEL50

Engine running-

Pos DVM lead at Dk/Lg Grn TPS wire at ECM and neg lead at ECM ground point on frame - .16 volts

Pos DVM lead at Dk/Lg Grn TPS wire at ECM and neg lead at neg batt post - .16 volts

Engine running during KOER test-

Pos DVM lead at Dk/Lg Grn TPS wire at ECM and neg lead at ECM ground point on frame - starts out at .16 volts, when idle goes up during test it continuosly modulates up and down- .16v-.17v-.18v-.17v.16v.17v.18v.17v.16v (I was holding the pos probe steady on the green wire. Neg lead hard wired to ground point. ) As soon as the test was over and idle went back to normal, voltage went back to a steady .16v

Did not check it driving the car as I could not figure out how to get a solid connection on the green TPS wire with the pos DVM lead without cutting and splicing the wire. I dont want to cut any wires unless there is no other option.

SFC ROCK- I think that it is probably a bad ground/wire somewhere. I just cant seem to find it. I cleaned and tightned all the ground points that I know of. Voltage stays steady at .16v when wiggling and shaking the harness as much possible.

HOTCOBRA03- Can you explain circuit 361 more clearly and what to check? I am not sure that I follow your line of thought.

Click to expand...

have u tested at just the tps and not the pcm...im assuming yes...pin 57/37 check in pin testsC was low yes.

90topdown said:

UPDATE

OK- I cut the black SIGRTN wire on the injector harness before the connector. Re-connected TPS. Ignition On-

Voltage on TP SIG (green) .20v to 1.36v linearly as throttle moved from close to WOT. DVM neg lead to batt

With SIGRTN cut, why did voltage jump to .20v from .16v??

BTW- I got a code 63 (low TPS voltage) when I did the KOER


Todd

Click to expand...

Redo the VREF-TP jumper voltage check, if the reading at the TP wire = VREF, you have another defective TPS or it might not be installed correctly on the TB. You need to make sure the TPS tabs are properly aligned with the the TB shaft, suggest to remove the TPS from the TB, connect it to the harness, and check its voltage output by manually rotating the disk.



You should be able to get it warrantied.... again, if required. After you do so, do not install the replacement TPS on the the throttle body, redo the voltage check with the TPS off the TB first. LUK

what am i missing?

1st test pin 26 to 46 at tps connector,passed yes...now most tps are non-adjustable,but some yes or to modify,,,on a type c you put the positive lead on pin 47 and the negitive on pin 46,at tps connector,than rotate till 1.0volts ........it doesnt sound like that from this story,,you had him cut pin 46 and test 47 to ground,,,,??????????????

Yep.... to ground..... and when I mention rotating it, I mean rotating the potentiometer cylinder with the TPS removed from the TB.

tps test

joel5.0 said:

Yep.... to ground..... and when I mention rotating it, I mean rotating the potentiometer cylinder with the TPS removed from the TB.

Click to expand...

so this test will tell if 46 is bad or that the problem lies in that circuit?....i just keep going over this...26 is .5v in 46 is signal return....47 watches change of volts 1.0 to 5.0 inside tps..following fords pin tests DH.....its a long story but recall 2 test done on pin 26 to 46 at pcm was good but 26 to 46 at tps harness didnt,,,am i wrong...

hotcobra03 said:

so this test will tell if 46 is bad or that the problem lies in that circuit?....i just keep going over this...26 is .5v in 46 is signal return....47 watches change of volts 1.0 to 5.0 inside tps..following fords pin tests DH.....its a long story but recall 2 test done on pin 26 to 46 at pcm was good but 26 to 46 at tps harness didnt,,,am i wrong...

Click to expand...

Nope.... it takes the possibility of an internal short to ground (= SIGRTN) in the TPS out of the picture, it only checks the actual voltage change through the variable resistor using an external ground reference point for the DVOM only.

failed test

you have tried almost everthing....remember you failed some test...the jumper wire that u just did was to generate code 53?????koeo was 53/23 present ,,,than the next you failed,,,,,pin 47 to 26 and 47 to 57,, than pin 47 to 40 and 47 to 60 46 to 47 thier was .66 ohms,,,than you failed pin testC ,,,pin 37 to self-test connector...look at the book we passed on to you closely... follow pin 51 thier is a break betweem dotted lines and cuts of circuit60 ? pin 60 is also in eec relay...have you tryed them yet,,,

90topdown said:

Update

All this is with SIGRTN wire cut

Ran jumper between VREF and TP signal terminals in TPS connector

Ignition on

- At pin 47, dk grn/lg grn wire near ECM connector - 4.93v
- VREF at TPS connector - 4.95v

Removed TPS from TB, manually rotated disk sensor, voltage on green wire went linearly from .19v to 1.45v while rotating disk.

FWIW, I currently have 3 different TPS sensors
Voltage at green wire, KOEO

TPS 1 - .17v original TPS with car
TPS 2 - .20v new Ford TPS
TPS 3- .17v new NAPA TPS

With 3 different TPS, I have gotten basically the same voltage reading so I doubt that it is a bad TPS sensor.

In installing the TPS, I normally set it on top of the TB, then turn it clockwise until screw holes line up.

Just for giggles, I tried setting it on top of the TB and turning it counter clockwise until the holes lined up but I got the same .17v reading.

Any ideas?? I'm stumped

Click to expand...

Check the graphical description of the situation, analyze it and LMK what do you see different.

answer

joel5.0 said:

Check the graphical description of the situation, analyze it and LMK what do you see different.

Click to expand...

i see up put .5v /pin 26 and jumped to 47,,and that gives .5v than when you move throttle volts will chang by .5v if tps is good...,,in side of tps 46 is removed and dvom is used as pin 47 would in the first place;;;just for ****s and giggles can he hook up a tps at the pcm and bypass all circuits than tps should read right?

DVOM set in 200kΩ, measure resistance between green and orange pins in the TPS connector, sensor disconnected, and check how the resistance varies while you rotate the pot disk. LUK

I have been watching this thread for a while and it has been bugging me. So here's my ideas on what to test and how to do it.

As with all checklist procedures, start at the top and work your way down. Do not skip any steps, as the results of the next test depend on the last test having completed satisfactorily


Theory of how it works:
The computer supplies 5 volt VREF to power 3 sensors. They are the TPS, EGR and MAP/BARO sensors. The use of a tightly regulated voltage insures that all sensors are accurate over a wide range of operating temperatures. Note that the VREF orange/white wire supplies two engine mounted sensors (TPS & EGR) and one firewall mounted sensor (MAP/BARO sensor). VREF also powers all the electronics inside the computer.

Tools needed:
DVM with good batteries. Know the difference between voltage (volts) and resistance (ohms) and how to measure them with your DVM. Make sure you know how to read voltages and resistances with you meter. Some DVM’s auto range and others require you to select the range. Be sure you understand the range selection process if your DVM does not auto range. Do not touch the probe tips while making resistance measurements. If you do, your measurements will be very wrong.

Two or three big safety pins. You may need them to probe the electrical connector plugs from the rear. Keep in mind that it may require some effort to make good connections to use your DVM. Flaky or intermittent connections can lead you down the wrong path.
#2 Philips screwdriver
¼” flat blade screwdriver.
5/16” socket
¼ drive ratchet
3” long 1/4 “ extension.
3/8” ratchet
10 MM deep socket or 10 mm socket & 3” extension.

Getting started:
Verify that VREF is good:

1.) The fist step is to dump the codes: if one of the sensors is shorting VREF to ground, you will get codes 22 (MAP/BARO sensor), 63 (TPS sensor), and 31 or 32 (EGR sensor). You will get all the codes if VREF is shorted to ground, not just one or two of them.
2.) The next step is to determine which sensor is causing the low VREF voltage.

A.) All sensors connected and installed correctly. Ignition off:
Locate the MAP/BARO sensor on the firewall behind the upper intake manifold. Insert one safety pin in the rear of the electrical connector where the black/white wire is connected. Insert another safety pin in the rear of the electrical connector where the orange/white wire is connected. Make sure the safety pins do not touch each other or metal parts of the body or engine. Connect the DVM or meter to the safety pins. If your meter is polarity sensitive, be sure that it is connected correctly: positive to the orange/white wire, negative to the black/white wire.

B.) Turn the ignition switch to Run, but do not start the engine. Note the voltage: it should be between 4.5 and 5.5 volts. If it is within range, go to step 5. If it is over 5.5 volts, go to step 7

C.) If the voltage is less that 1 volt, turn off the ignition switch and ground the DVM or meter negative lead to the battery post. Turn the ignition switch to the Run position but do not start the engine. Recheck the voltage readings. If the voltage reads 4.5 to 5.5 volts, the VREF is good and the signal ground to the MAP/BARO sensor is bad.

D.) If the voltage is still below 4.5 volts, turn off the ignition switch and disconnect the electrical connector from the MAP/BARO sensor. Turn the ignition switch to the Run position but do not start the engine and recheck the voltage readings. If the voltage reads 4.5 to 5.5 volts, the VREF is good and the MAP/BARO sensor is bad. Time to replace the sensor. You will find that you will get a code 22 if the MAP/BARO sensor is bad. Leave the MAP/BARO sensor disconnected until the other sensors have been tested.

3.) TPS sensor connected and installed correctly. Ignition off:
The TPS is mounted on the top side of the throttle body. Insert one safety pin in the rear of the electrical connector where the black/white wire is connected. Insert another safety pin in the rear of the electrical connector where the orange/white wire is connected. Make sure the safety pins do not touch each other or metal parts of the body or engine. Connect the DVM or meter to the safety pins. If your meter is polarity sensitive, be sure that it is connected correctly: positive to the orange/white wire, negative to the black/white wire

A.) Turn the ignition switch to Run, but do not start the engine. Note the voltage: it should be between 4.5 and 5.5 volts. If it is within range, go to step 4 to check VREF on the EGR sensor.

B.) If the voltage is less that 1 volt, turn off the ignition switch and ground the DVM or meter negative lead to the battery post. Turn the ignition switch to the Run position but do not start the engine and recheck the voltage readings. If the voltage reads 4.5 to 5.5 volts, the VREF is good and the signal ground to the TPS sensor is bad.

C.) If the voltage is still below 4.5 volts, turn off the ignition switch and disconnect the electrical connector from the TPS sensor. Turn the ignition switch to the Run position but do not start the engine. Recheck the voltage readings. If the voltage reads 4.5 to 5.5 volts, the VREF is good and the TPS sensor is bad. Time to replace the sensor.

D.) If the voltage is still below 4.5 volts, Leave the TPS sensor disconnected until the other sensors have been tested. Then go to step 4

4.) EGR sensor connected and installed correctly. Ignition off:
The EGR is mounted on the back side of the EGR valve. Insert one safety pin in the rear of the electrical connector where the black/white wire is connected. Insert another safety pin in the rear of the electrical connector where the orange/white wire is connected. Make sure the safety pins do not touch each other or metal parts of the body or engine. Connect the DVM or meter to the safety pins. If your meter is polarity sensitive, be sure that it is connected correctly: positive to the orange/white wire, negative to the black/white wire

A.) Turn the ignition switch to Run, but do not start the engine. Note the voltage: it should be between 4.5 and 5.5 volts. If it is within range, go to step 5.

B.) If the voltage is less that 1 volt, turn off the ignition switch and ground the DVM or meter negative lead to the battery post. Turn the ignition switch to the Run position but do not start the engine and recheck the voltage readings. If the voltage reads 4.5 to 5.5 volts, the VREF is good and the signal ground to the EGR sensor is bad.

C.) If the voltage is still below 4.5 volts, turn off the ignition switch and disconnect the electrical connector from the EGR sensor. Turn the ignition switch to the Run position but do not start the engine. Recheck the voltage readings. If the voltage reads 4.5 to 5.5 volts, the VREF is good and the EGR sensor is bad. Time to replace the sensor.

D.) If the voltage is still below 4.5 volts, go to step 5 to check for wiring faults.

5.) VREF less that 4.5 volts with all sensors disconnected:
Disconnect the battery negative cable at the battery. Remove the passenger side kick panel and then loosen the 10 MM hex bolt that secures the computer wiring harness connector to the computer. Measure the resistance between pin 26 on the computer and the orange/white wires on the MAP/BARO, TPS and EGR sensors. You should see less that 1.5 ohms on each of the orange/white wires and pin 26. More than that indicates wiring problem.

Computer wiring harness connecter as viewed from the pin side.


The 10 pin connectors that join the engine fuel injector harness to the main harness are prime suspects.

Notice that pin 1 on the black connector is VREF. If this pin has a bad connection or broken wire, both the TPS and EGR will have no or low VREF voltage. A high resistance on only one wire is an indication of a broken wire or bad connection inside the fuel injector wiring harness.





If the above resistance test passes, move the meter lead from pin 26 to the ground point next to the computer. Then measure the resistance between the orange/white wire on any of the sensors and ground. You should see greater than 1 Megohm or an infinite open circuit. Reconnect the sensors and the computer, reconnect the battery negative cable to the battery.

6.) At this point, you have verified that all the sensors that use VREF have the proper supply voltage. If you still do not have proper VREF, then the problem is inside the computer. This is a replace the computer with a known good unit and retest to see if you get the same codes 22 (MAP/BARO sensor), 63 (TPS sensor), and 31 or 32 (EGR sensor). All the codes should have cleared unless you have some faulty sensors.

7.) VREF exceeds 5.5 volts:
Disconnect the battery negative cable at the battery. Remove the passenger side kick panel and then loosen the 10 MM hex bolt that secures the computer wiring harness connector to the computer. Pull the wiring harness connector down so that it disconnects from the computer. Then measure the resistance between the orange/white wire on any of the sensors and pin 1. Then measure the resistance between the orange/white wire on any of the sensors and pin 37. You should see greater than 1 Megohm or an infinite open circuit in both cases. Less than 1 Megohm indicates a wiring problem.
If the resistance check is good, then the problem is inside the computer. This is a replace the computer with a known good unit and retest to see if you get the same high voltage readings. If you do, then your DVM may be whacko…

VREF is verified as good, sensor output is still low:
8.) One or more sensors get a low output voltage code (63 - TPS sensor, or 31 or 32 - EGR sensor). After you have replaced the sensor and are still getting a low voltage code or low voltage reading, it is time to go hunting. By completing steps 1-7, you have verified that you have good VREF and it is not a cause of your problem.
Disconnect the battery negative cable at the battery. Remove the passenger side kick panel and then loosen the 10 MM hex bolt that secures the computer wiring harness connector to the computer. Pull the wiring harness connector down so that it disconnects from the computer.

Make sure that the TPS & EGR sensors are disconnected while performing the following tests. If you don't disconnect them, you will get incorrect measurements.

A.) TPS sensor: measure the resistance between the TPS green/lt green wire and pin 47. You should see less than 1.5 ohms. More than that indicates a wiring problem. Then measure the resistance between the green/lt green wire on the TPS sensor and ground. You should see greater than 1 Megohm or an infinite open circuit.
Adjust the TPS sensor as follows:
Set the TPS voltage at .5- 1.1 range. Because of the variables involved with the tolerances of both computer and DVM, I would shoot for somewhere between .6 and 1.0 volts. Unless you have a Fluke or other high grade DVM, the second digit past the decimal point on cheap DVM’s is probably fantasy. Since the computer zeros out the TPS voltage every time it powers up, playing with the settings isn't an effective aid to performance or drivability. The main purpose of checking the TPS is to make sure it isn't way out of range and causing problems. Put the safety pins in the Dark Green/Lt green wire and Black/White wire. Make sure the ignition switch is in the Run position but the engine isn't running.

B.) EGR sensor: measure the resistance between the EGR brown/lt green wire and pin 27. You should see less than 1.5 ohms. More than that indicates a wiring problem. Then measure the resistance between the brown /lt green wire on the EGR sensor and ground. You should see greater than 1 Megohm or an infinite open circuit.

C.) If both the above tests pass, then the problem is inside the computer. This is a replace the computer with a known good unit and retest to see if you get the same low voltage readings. If you do, then your DVM may be whacko…

90topdown said:

Diagram 1 is correct with the exception that VREF +/- 5v and TP sig +/- .17v occurs both with SIGRTN connected and cut.

In looking at the diagram, it makes no sense, but if you note all of my last voltage readings were with SIGRTN cut.

Diagram 2 is 100% correct.

Looks like a bad TPS sensor to me, but if that is true, how the heck did I get 3 bad sensors in a row form different sources that give the same reading???????

Doesn't make sense to me...........

Click to expand...

It does make sense, if you use the variable resistor the TPS is, and check voltage between VREF and TP, you read the out of range values you've posted, with the SIGRTN wire removed from the TPS....... the resistor portion is removed from the TPS, TP wire reading should be = to VREF input, which is exactly the same condition as replacing the variable resistor with a jumper. Since TP = VREF when the TPS is replaced with a jumper wire..... therefore........ what is the logical component with the fault.

BTW.... for S&G's, I just confirmed the results above using a KGU TPS in a Ford I have in the shop for a valve train upgrade.

Anyway, measure the resistance at the TPS VREF and TP wires.... it should start ~3.3kΩ closed throttle and drop to ~.26kΩ (260Ω) @WOT. LUK

Go back and look at the block diagram I posted.
The black/white wire is the computer signal ground for the MAP, TPS & EGR.
Measuring resistance between the green TPS or brown EGR and ground will
give undetermined results.

To test the signal ground, disconnect the battery negative cable.
Then measure the low ohms reading between the black/white
wire on the TPS or EGR and the negative battery cable terminal.
You should see less than 2 ohms.

The ground inside the car is not the computer power ground.
It is the shield ground for the TFI wiring.

The computer has its own dedicated power ground that
comes off the ground pigtail on the battery ground wire. Due to
it's proximity to the battery, it may become corroded by acid
fumes from the battery. It is a black cylinder about 2 1/2" long
by 1" diameter with a black/lt green wire. You'll find it up next to
the starter solenoid where the wire goes into the wiring harness

The battery common ground is a 10 gauge pigtail with the computer ground
attached to it.

Picture courtesy timewarped1972

short in harness

90topdown said:

UPDATE

Here are the latest:

Joel50-
DVOM set at 200k, resistance between green and orange pins in the TPS connector - 03.8
DVOM set at 200k, resistance between green and orange wires, sensor disconnected, rotating pot disk- varies between 03.8 - 00.3


JRichker-
1) KOEO codes-
21- ECT out of range
24-ACT out of range
96- secondary fuel pump circuit failure
10-
63- TP below minimum voltage
96- secondary fuel pump circuit failure

1B) 4.92 v between black and orange wires at MAP sensor

7) Selector set on 20M ohm
Pin 1 - TPS orange 11.35 and rising
Pin 1 - EGR orange 11.35 and rising
Pin1 - MAP orange 11.35 and rising

Pin 37 - TPS orange 13.65 and rising
Pin 37 - EGR orange 13.65 and rising
Pin 37 - MAP orange 12.57 and rising

8A) Selector set on 200 ohm
Resistance between TPS green and pin 47- .4 ohm

Resistance between pin 27 and EGR brown/lt green wire - .4 ohm

8B) Selector set at 20M ohm

Resistance between green wire on TPS and ground- -1- meter did not move
Reisitance between EGR brown wire and ground- -1- meter did not move

Tried same test with meter set on 200 ohm. Got same result. Meter did not move on either TPS or EGR ground test. I used the TB for a grounding point.

Looks like a ground problem??


FWIW- I have cleaned and tightened all the ground wires that I am aware of
- neg batt to engine
- neg batt to front radiator support
- neg batt to engine harness ground point by solenoid
- engine harness ground point by solenoid to engine block
- engine block to frame
- engine block to firewall
- injector harness ground goes to firewall not rear cyl head
- eec ground point underneath EEC in cabin

I am missing any ground points??

Thoughts??

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well you wont like my next choise....take out harness completly and check every wire for continuity...you have missed something,,or more than just injector harness was changed and we are missing something...when i helped out onther guy we went over the 60 pin connector and found a different wire on pin 30,,just one wire caysed him hell,,,but you need to start over with basics or pull harness ..its been a long time here as JR has stated...thier was another guy ..7months and car still not right,,he found his problem going back to basics and on step 2 was fixed,,,dont loose hope ,,its only nuts and bolts...

jrichker and hotcobra03 seem to have you back on the right track with checking the wiring the correct way. When I had my ground issue I followed the following steps and they lead me right to the problem. Post the results if choose to follow these.

•Check Self-Test Input circuit on Pin 48 at computer harness for shorts to ground.
•Replace faulty wiring.
•Remove check engine light bulb and check Self-Test Output circuit for shorts to ground.
•Replace faulty wiring.
•Check Engine Light for damage.
•Replace faulty light bulb.
•Measure resistance between battery negative post and pins 20, 40, and 60 at the computer harness.
•Resistance must be less than 5.0 ohms.
•Replace faulty wiring between computer and battery if not.
•Turn key to ON with engine OFF and computer removed. Measure voltage on pins 1, 37, and 57. Must be above 10.5 volts and within 1.0 volt of each other.
•Replace faulty wiring between computer and battery if not.
•Turn key ON with engine OFF and computer reinstalled. Measure voltage between Pin 26 and 46 (voltage reference and signal return) must be between 4.0-6.0 volts.
•Replace faulty wiring and sensors.
•Measure resistance between Pin 46 and Pins 40 and 60 at the computer harness, must be less than 5.0 ohms.