OBD 1 code 15.

Johnny H.

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Sep 8, 2017
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Hey gents. It’s my first time posting in here. I have a 93 Cobra that will run fine then just shut off and the only way it will start up is if I disconnect the battery and connect it again. I went through the process of elimination by replacing the tfi module, ignition coil, fuel pump relay and cap and rotor. Car will still not start up it just cranks. I’m now down to testing the ecm. Does anyone have a pin diagram for the ecm and what are the parameters for each test. I know it needs 12 volts for power but as far as everything else do I test for ohms to voltage? I hope its not a faulty ecm. Hard to find an X3Z ecm at a parts store.
Mods so far is BBK long tube, BBK off road H, magnaflow cat back, B303 cam, sct chip and MSD box and dizzy. Maximum Motorsports upper and adjustable lower control arms, 3:73 gears and a fabreeze air freshener.
 
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General karthief

wonder how much it would cost to ship you a pair
Mod Dude
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Ok, first off that fabreeze stuff will screw up your 'in cabin fresh air monitor' and will cause injector pain making the car run lean, best way to figure out if that is what is causing the problem is to go through the 'cranks but no start checklist', seriously, it will show you how to check for codes and has step by step instructions on how to deal with your problem, read through it to get familiar then do the steps in order, jrichter and other put it together and it works. Here's a link:
https://www.stangnet.com/mustang-fo...start-checklist-fuel-injected-mustangs.787471
 

Johnny H.

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Sep 8, 2017
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Thanks for the info guys. I’m still not finding the root of my problems yet. I still need to troubleshoot the fuse links, pip and ignition switch. Most of the no start checklist is good including removing the sct chip. I’m chipping away on the list and it can be time consuming. Will a digital clamp meter work to check the fuse links? I did a visual and physical inspection of the fuse links and they look good not brittle or anything indicating being blown. Not sure how to check the pip and I’ve looked for part replacements and can’t find the part. Maybe I can send the distributor to MSD to get repaired. Oh by the way the “cabin fresh air monitor checked out fine” so fabreeze gets to stay for a bit. Lol.
 
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jrichker

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@Johnny H

The code 15 indicates more that just an external chip for the computer

Code 15 or 511 - No Keep Alive Memory power to PCM pin 1 or bad PCM (Memory Test Failure).

Revised 15-Nov-2015 to clarify the difference between erasing stored codes and erasing learned adaptive computer settings.

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 may be bad and the computer is faulty. Read on further to make this determination, since there are some exceptions.

Clearing the codes by pressing a button on the scan tool or disconnecting the test jumper used to start the code dump does not erase the “learned settings”. Disconnecting the computer from the wiring harness or disconnecting the battery (either power or ground cable) will erase the “learned settings” If the computer has to "relearn" all the optimum settings every time it powers up, the initial 15-30 minutes of operation may exhibit surges, poor low speed performance, and rough idle.

Note that some aftermarket chips will cause code 15 to set. Disconnect the battery and remove the chip, reconnect the battery and retest. If you have a custom burned chip using the data gathered from a dyno session, this may not be advisable since it may drastically alter the fuel/air and timing tables.

For stock engines or engines with minor modifications (OEM cylinder heads, stock 19 LB injectors, no NO2 or pressurized induction).
Before replacing the computer, remove the battery ground cable for about 20 minutes. This will clear all the codes and “learned settings”. 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 http://www.veryuseful.com/mustang/tech/engine/

Diagram courtesy of Tmoss & Stang&2birds
88-91_5.0_EEC_Wiring_Diagram.gif


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

http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif
 

Johnny H.

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Sep 8, 2017
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Well after months of troubleshooting I found my problem. It was the ignition pickup in the distributor. I bought a msd street fire and replaced the msd billet. It fired right up. Now I just need to get the timing set because it runs kinda rough. I need to invest in a timing light. Good thing this wasn’t my daily driver. Thanks for all the help gents.
 

jrichker

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Well after months of troubleshooting I found my problem. It was the ignition pickup in the distributor. I bought a msd street fire and replaced the msd billet. It fired right up. Now I just need to get the timing set because it runs kinda rough. I need to invest in a timing light. Good thing this wasn’t my daily driver. Thanks for all the help gents.
Glad that you found and fixed the problem.

Here's some more help with setting the ignition timing...

Putting the distributor back in and setting the timing.

Revised 15-Apr-2016 to add fix for TFI hitting the thermostat housing while trying to set the base timing at 14°.

You can forget about anything beyond this point if you don't have access to a timing light. You will never get the timing set right without one.

Note: If you don't have access to a timing light, most of the larger auto parts stores will rent or loan one if you have a credit card or leave a cash deposit.



Putting the distributor back in is fairly simple. Pull #1 sparkplug, put your finger in the sparkplug hole, crank the engine until you feel compression. Then line up the TDC mark on the balancer with the pointer on the engine block.

The distributor starts out with the #1 plug wire lined up at about 12:00 with you facing it. Align the rotor to about 11:00, since it will turn clockwise as it slides into place.

Align the distributor rotor up with the #1 position marked on the cap, slide the distributor down into the block, (you may have to wiggle the rotor slightly to get the gear to engage) and then note where the rotor is pointing.
If it still lines up with #1 position on the cap, install the clamp and bolt. If not, pull it out and turn 1 tooth forwards or backwards and try again. Put the #1 spark plug back in and tighten it down, put the clamp on the distributor, but don't tighten it too much, as you will have to move the distributor to set the timing. Note that there is no such thing as one tooth off on a 5.0 Mustang if you follow the spark plug wire order on the distributor cap. If it doesn't align perfectly with #1 position, you can turn the distributor until it does. The only problem is that if you are too far one way or the other, you can't turn the distributor enough to get the 10-14 degree optimum timing range. If the TFI prevents the distributor from being turned enough to get 14°, there is a simple fix. Pull the distributor out and turn the rotor 1 tooth counterclockwise Don't move the wires from the positions shown on the cap on fuel injected engines!!!! The #1 position cast into the cap MUST have the spark plug wire for #1 cylinder in it. Do it differently and the timing for the fuel injectors will be off. The computer uses the PIP sensor to time injector operation by sensing the wide slot in the PIP sensor shutter wheel. If the injector timing of #1 and the firing of #1 do not occur at the right time, the injector timing for all other cylinders will be affected.

Setting the timing:
Paint the mark on the harmonic balancer with paint -choose 10 degrees BTC or 14 degrees BTC or something else if you have NO2 or other power adder. I try to paint TDC red, 10 degrees BTC white and 14 degrees BTC blue.

10 degrees BTC is towards the drivers side marks.

Note: setting the timing beyond the 10 degree mark will give you a little more low speed acceleration. BUT you will need to run 93 octane to avoid pinging and engine damage. Pinging is very hard to hear at full throttle, so it could be present and you would not hear it.

Simplified diagram of what it looks like. Not all the marks are shown for ease of viewing.

ATC ' ' ' ' ' ' ' ' ' '!' ' ' ' ' ' ' ' ' ' BTC
---------------- > Direction of Rotation as viewed standing in front of the engine.

The ' is 2 degrees.
The ! is TDC
The ' is 10 degrees BTC
Set the timing 5 marks BTC. Or if you prefer, 5 marks towards the driver's side to get 10 degrees.

To get 14 degrees, set it 7 marks BTC. Or if you prefer, 7 marks towards the driver's side to get 14 degrees.

The paint marks you make are your friends if you do it correctly. They are much easier to see than the marks machined into the harmonic balancer hub.

At this point hook up all the wires, get out the timing light. Connect timing light up to battery & #1 spark plug. Then start the engine.

Remove the SPOUT connector (do a search if you want a picture of the SPOUT connector) It is the 2 pin rectangular plug on the distributor wiring harness. Only the EFI Mustang engines have a SPOUT. If yours is not EFI, check for a SPOUT: if you don’t find one, skip any instructions regarding the SPOUT
Warning: there are only two places the SPOUT should be when you time the engine. The first place is in your pocket while you are setting the timing and the second is back in the harness when you finish. The little bugger is too easy to lose and too hard to find a replacement.

Start engine, loosen distributor hold down with a 1/2" universal socket. Shine the timing light on the marks and turn the distributor until the mark lines up with the edge of the timing pointer. Tighten down the distributor hold down bolt, Replace the SPOUT connector and you are done.

The HO firing order is 1-3-7-2-6-5-4-8.
Non HO firing order is 1-5-4-2-6-3-7-8

 

Johnny H.

Member
Sep 8, 2017
6
2
13
47
Glad that you found and fixed the problem.

Here's some more help with setting the ignition timing...

Putting the distributor back in and setting the timing.

Revised 15-Apr-2016 to add fix for TFI hitting the thermostat housing while trying to set the base timing at 14°.

You can forget about anything beyond this point if you don't have access to a timing light. You will never get the timing set right without one.

Note: If you don't have access to a timing light, most of the larger auto parts stores will rent or loan one if you have a credit card or leave a cash deposit.



Putting the distributor back in is fairly simple. Pull #1 sparkplug, put your finger in the sparkplug hole, crank the engine until you feel compression. Then line up the TDC mark on the balancer with the pointer on the engine block.

The distributor starts out with the #1 plug wire lined up at about 12:00 with you facing it. Align the rotor to about 11:00, since it will turn clockwise as it slides into place.

Align the distributor rotor up with the #1 position marked on the cap, slide the distributor down into the block, (you may have to wiggle the rotor slightly to get the gear to engage) and then note where the rotor is pointing.
If it still lines up with #1 position on the cap, install the clamp and bolt. If not, pull it out and turn 1 tooth forwards or backwards and try again. Put the #1 spark plug back in and tighten it down, put the clamp on the distributor, but don't tighten it too much, as you will have to move the distributor to set the timing. Note that there is no such thing as one tooth off on a 5.0 Mustang if you follow the spark plug wire order on the distributor cap. If it doesn't align perfectly with #1 position, you can turn the distributor until it does. The only problem is that if you are too far one way or the other, you can't turn the distributor enough to get the 10-14 degree optimum timing range. If the TFI prevents the distributor from being turned enough to get 14°, there is a simple fix. Pull the distributor out and turn the rotor 1 tooth counterclockwise Don't move the wires from the positions shown on the cap on fuel injected engines!!!! The #1 position cast into the cap MUST have the spark plug wire for #1 cylinder in it. Do it differently and the timing for the fuel injectors will be off. The computer uses the PIP sensor to time injector operation by sensing the wide slot in the PIP sensor shutter wheel. If the injector timing of #1 and the firing of #1 do not occur at the right time, the injector timing for all other cylinders will be affected.

Setting the timing:
Paint the mark on the harmonic balancer with paint -choose 10 degrees BTC or 14 degrees BTC or something else if you have NO2 or other power adder. I try to paint TDC red, 10 degrees BTC white and 14 degrees BTC blue.

10 degrees BTC is towards the drivers side marks.

Note: setting the timing beyond the 10 degree mark will give you a little more low speed acceleration. BUT you will need to run 93 octane to avoid pinging and engine damage. Pinging is very hard to hear at full throttle, so it could be present and you would not hear it.

Simplified diagram of what it looks like. Not all the marks are shown for ease of viewing.

ATC ' ' ' ' ' ' ' ' ' '!' ' ' ' ' ' ' ' ' ' BTC
---------------- > Direction of Rotation as viewed standing in front of the engine.

The ' is 2 degrees.
The ! is TDC
The ' is 10 degrees BTC
Set the timing 5 marks BTC. Or if you prefer, 5 marks towards the driver's side to get 10 degrees.

To get 14 degrees, set it 7 marks BTC. Or if you prefer, 7 marks towards the driver's side to get 14 degrees.

The paint marks you make are your friends if you do it correctly. They are much easier to see than the marks machined into the harmonic balancer hub.

At this point hook up all the wires, get out the timing light. Connect timing light up to battery & #1 spark plug. Then start the engine.

Remove the SPOUT connector (do a search if you want a picture of the SPOUT connector) It is the 2 pin rectangular plug on the distributor wiring harness. Only the EFI Mustang engines have a SPOUT. If yours is not EFI, check for a SPOUT: if you don’t find one, skip any instructions regarding the SPOUT
Warning: there are only two places the SPOUT should be when you time the engine. The first place is in your pocket while you are setting the timing and the second is back in the harness when you finish. The little bugger is too easy to lose and too hard to find a replacement.

Start engine, loosen distributor hold down with a 1/2" universal socket. Shine the timing light on the marks and turn the distributor until the mark lines up with the edge of the timing pointer. Tighten down the distributor hold down bolt, Replace the SPOUT connector and you are done.

The HO firing order is 1-3-7-2-6-5-4-8.
Non HO firing order is 1-5-4-2-6-3-7-8

Thanks for all the help. I wish I had 1/10 of the knowledge that you have on mustangs. Fox bodies has been a never ending story when it comes to its little quirks that seem to stymie some owners. I have gone through all of your checklist and have found things I never knew could be a problem. Now that my cobra is running and the timing set I still have idle issues. I pulled codes 15,16 and 19. I have checked the voltage at the injector harness and got 11.58 volts (haven’t started the car in about a week) and pins 37 and 57 at 11.58 volts. For the life of me I just can’t find the eec relay. I removed the glove box and nothing. Maybe I need to remove the dash? Could it be that my eec/pcm has taken a dump?
 

Johnny H.

Member
Sep 8, 2017
6
2
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Can you pm me the contact info on that repair shop, I have one that needs looked at.
This a copy of the email I received.

Thanks for speaking on the Mustang! As we discussed, we offer repair services for this at only $149.00 + return shipping. This includes the Diagnostic Evaluation Service, the repair, and includes a lifetime warranty. Our turnaround time on a repair is generally only 3 business days, and it does NOT require any programming by you.

All you need to do to send that in for repair is to give me a call at my direct number below, so I can set up a repair order for you, and then fill out the attached form and send it in with the module to the address on the form.

Thanks,


Adam
904-990-5139
Nationwide Parts Distributors & Module Experts

6873 Phillips Industrial Blvd suite “B”
Jacksonville Florida 32256
Fax: 904-680-5119
[email protected]
 
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CUAviator

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Jan 11, 2015
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8
I too have a chip in my computer and get a code 15. When I pull the chip, the code 15 disappears (but I get a thousand other codes that the chip has been programmed to override...emissions stuff mostly).

*** My question is - is there a way to override the code 15 with the chip installed so that the KAM remains intact and is not trying to relearn every time I start the car?
 

jrichker

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@CUAviator

The reason for the code 15 is that the software contains what is commonly called a Checksum. Its purpose is to notify the computer or users that the software has been modified. This modification is either intentionally by deliberate change in the software loaded into the ROM, or by a failure in the ROM chip that contains the software. The proper fix is for the person who wrote the offending software to change the checksum. Depending on the design of the computer, this may or may not the practical or possible.
 

CUAviator

Member
Jan 11, 2015
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@CUAviator

The reason for the code 15 is that the software contains what is commonly called a Checksum. Its purpose is to notify the computer or users that the software has been modified. This modification is either intentionally by deliberate change in the software loaded into the ROM, or by a failure in the ROM chip that contains the software. The proper fix is for the person who wrote the offending software to change the checksum. Depending on the design of the computer, this may or may not the practical or possible.
Do you mind if I PM you?
 

jrichker

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Do you mind if I PM you?
Sorry, except for very rare exceptions, I do not answer requests for technical assistance via PM or email.

Please make your post in Stangnet's 5.0 Tech forum
( https://www.stangnet.com/mustang-forums/forums/fox-5-0-mustang/ ) and I will try to help. The space for a quality reply is severely limited in a PM and emails often do not allow the simple posting of diagrams.

If you have an electrical problem, please include the model year of your Mustang. The electrical wiring scheme changed at least 4 times in 79-93 Mustangs. Include the main color & stripe color of wires in question. It prevents making the mistake of counting the pins from the wrong end of a connector and helps to identify a particular circuit function. If you used wiring harnesses from different years or cars other that Fox body Mustangs, please pass that information along as well.

I find that the experience and ideas of other members contributes a great deal to the troubleshooting process. They will often think of things or ask questions that I had not thought of.

If you like, you can send me a PM with the Stangnet post ID, since it will help me find your post.

Joe R.
 

CUAviator

Member
Jan 11, 2015
70
1
8
Sorry, except for very rare exceptions, I do not answer requests for technical assistance via PM or email.

Please make your post in Stangnet's 5.0 Tech forum
( https://www.stangnet.com/mustang-forums/forums/fox-5-0-mustang/ ) and I will try to help. The space for a quality reply is severely limited in a PM and emails often do not allow the simple posting of diagrams.

If you have an electrical problem, please include the model year of your Mustang. The electrical wiring scheme changed at least 4 times in 79-93 Mustangs. Include the main color & stripe color of wires in question. It prevents making the mistake of counting the pins from the wrong end of a connector and helps to identify a particular circuit function. If you used wiring harnesses from different years or cars other that Fox body Mustangs, please pass that information along as well.

I find that the experience and ideas of other members contributes a great deal to the troubleshooting process. They will often think of things or ask questions that I had not thought of.

If you like, you can send me a PM with the Stangnet post ID, since it will help me find your post.

Joe R.
Rog. Good points. Thanks.
 
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