2004 Mach 1 crank but no start. dying inside

COramprat

...I can take it. I think.
Mod Dude
Mar 2, 2003
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I'm still going back to where the issues started and that's with the loading of the car on the trailer. You have continuity to the fuel pump but no power. Something in that is where I'm leaning. Hypothetically where do you lose power in that system? I guess it's plausible that something shorted and caused the PCM to lose contact with the fuel pump. It's just odd nothing else is affected. So the chip/tune sounds like the culprit. You also don't have contact for PATS.

Let's take a stab in the dark. Couldn't hurt.
Follow the instructions about 5 posts down here:


Also I'm tagging @wmburns and see if he can chime in.
 
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gavinmgrant

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May 23, 2022
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I'm still going back to where the issues started and that's with the loading of the car on the trailer. You have continuity to the fuel pump but no power. Something in that is where I'm leaning. Hypothetically where do you lose power in that system? I guess it's plausible that something shorted and caused the PCM to lose contact with the fuel pump. It's just odd nothing else is affected. So the chip/tune sounds like the culprit. You also don't have contact for PATS.

Let's take a stab in the dark. Couldn't hurt.
Follow the instructions about 5 posts down here:


Also I'm tagging @wmburns and see if he can chime in.
The fuel pump harness all shot good continuity, correct. 12v is making it to the FPDM, so I figured either the module is bad or the ground was bad. Ground shot good, perfect 0.1 ohms. Didn’t see any breaks in the wires. 12v is getting to the FPDM, but 1.8v coming out like I said in the video.
 

gavinmgrant

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May 23, 2022
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I'm still going back to where the issues started and that's with the loading of the car on the trailer. You have continuity to the fuel pump but no power. Something in that is where I'm leaning. Hypothetically where do you lose power in that system? I guess it's plausible that something shorted and caused the PCM to lose contact with the fuel pump. It's just odd nothing else is affected. So the chip/tune sounds like the culprit. You also don't have contact for PATS.

Let's take a stab in the dark. Couldn't hurt.
Follow the instructions about 5 posts down here:


Also I'm tagging @wmburns and see if he can chime in.
And I’ve followed A LOT of posts from Burns. Specifically that link as well. All the grounds have been good, etc.
 

Mach1.0

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May 29, 2022
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Hello everyone,

So I purchased a 2004 Mach 1 with 90,000 miles that needed some work about a month ago. I've been slowly working on my list of things to fix or repair on the car. It ran great when I took it for a test drive. Drove it for about an hour before I decided to take it home. I was very happy with the way it ran at the time. The person I bought it from did a battery relocation kit to the trunk but ran the power wire underneath the car along the subframe connectors. Here is where it gets interesting and why the battery relocation is important information.

I rented a Uhaul truck and trailer to go pick it up because I did not want to drive it 600 miles back to Texas from New Mexico (where I bought it.) So myself and the owner at the time drove it onto the trailer and the car got a bit stuck going up the ramps of the trailer, it high centered essentially and shut off. I thought he may have just stalled it. But the car would not start. I looked under the car and noticed the battery wire that was zip tied to the subframe connectors were slashed and sparking against the trailer. The exterior and interior lights would come on but were extremely dim and the car would not crank at the time. So we unhooked the battery for safety reasons and pushed the car up on the trailer using a few extra bodies.

I get it home in the early morning and unload it. Wrap the exposed battery wire in electrical tape temporarily to attempt to get the car up my steep driveway. It starts just fine and I'm able to get it into the garage. I immediately disconnect the battery again for safety reasons. I ended up doing a much better battery relocation to the trunk by routing the battery power cable through the cabin of the car and of course a new 1/0 gauge wire plus a circuit breaker for safety.

While I had the car in my garage sitting, I added a bus bar (metal bar/post with 4 terminals) that has my battery wire powering it. This bus bar also has the starter wire and the engine bay fuse box wire attached to it. I also upped the gauge of the alternator wire and the fuse box wire to 1/0 gauge as well. I also upped the gauge of the engine to chassis ground wire and the battery ground wire to 1/0 gauge. No problems doing this easy wire upgrade.

I go to start it up for the first time after this upgrade. At this point it has been about two weeks since I brought this car home, I do not have a lot of time during the week to work on it. It cranks but doesn't start. I do not hear the fuel pump prime at all when the key is turned to the run position. Weird. So I start doing some digging around for anything disconnected. Could not find anything. The THEFT light is flashing as soon as I put the key in the run position. It ran with the theft light flashing when I took it for a test drive. No big deal, my 2001 GT was the same way after it got tuned. This Mach 1 is tuned by a very reputable tuner in New Mexico so I did not think much of it at the time. The inertia switch is pushed in, 12v is getting to the FPDM (fuel pump driver module) via the BLACK/PINK wire which comes directly from the CCRM and through the inertia switch but only 1.8v is coming out going to the fuel pump on BROWN/PINK. I shoot the ground of the FPDM and it's all good. I shoot the wires for continuity between the FPDM and the fuel pump, all good there. I can disconnect the fuel pump connector and wire it straight to a 12v battery and the fuel pump will run just fine. So I changed the FPDM anyways just to rule it out. Same problem, cranks but doesn't start.

So I spray some carb cleaner in the intake and the car fires up for about 3 seconds then dies. So it's clear the engine is obviously not getting fuel. Battery has 12v, check engine light IS NOT on during cranking.

So I moved on to attempt to address the THEFT light issue, since from what I understand if the THEFT system is engaged, the PCM will not activate the fuel pump although 12v may be getting to the FPDM. Correct me if I am wrong on that. So the car only came with one key from the previous owner. I decided to change the PATS transceiver in the steering column and have a locksmith come out and program new keys and "sync" the theft system again. Still the same thing. Cranks forever but does not start. The technician only charged me a $40 service fee, so that was cool on him since he didn't technically fix anything. He hooked up a different scan tool and the scan tool was not able to pull the VIN number for the car via the OBD2 port. He was able to clear a few codes which did not seem to be related to the problem (ABS something or other) but he got to a point trying to look at the PATS system in real time where the scan tool would no longer communicate with the PCM. It would say "cannot communicate with PCM."

I shot a lot of wires for shorts to ground, opens, and shot all the grounds according to a pin-out diagram of the PCM connector. All of my fuses are good. I shot continuity through the fuel pump fuse F1.14, good there. I have 12v going to F1.14. I shot 12v at fuses F2.2, F2.8, and F2.34. All had 12v. I cannot find anything wrong, no blown fuses. I cleaned up a few grounds here and there and redid some terminals, but never found anything wrong. The odometer IS NOT dashed, it reads mileage properly.

At this point I am leaning into getting my PCM repaired or replaced. I feel the battery power wire arcing against the trailer when I picked it up may have done some damage downstream to the PCM. Does anyone have ANYTHING else I should look at? I am open to any ideas. Sorry for the long post but I feel all of the information I have provided is necessary. Thanks.
Hey, few questions and an article that might help.
1. Can you communicate with your OBD port KOEO and KOER?
2. Have you tried disconnecting the ABS module then trying to crank? The ABS is on the SCP network.
3. Do you have access to an oscilloscope?
4. Here’s a link to a good article explaining how the FPDM and ECM work together:
 

gavinmgrant

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May 23, 2022
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Hey, few questions and an article that might help.
1. Can you communicate with your OBD port KOEO and KOER?
2. Have you tried disconnecting the ABS module then trying to crank? The ABS is on the SCP network.
3. Do you have access to an oscilloscope?
4. Here’s a link to a good article explaining how the FPDM and ECM work together:
Thank you for the comment.

I pulled the fuse to the ABS module, of course the ABS light came on, the car will still crank but not start.

I can only pull code P1233 with the chip installed with the key in the run position. I get “error” with the key in the ignition but not in run. I get “error”in run and key in but I’m off position with this chip removed. With chip removed, still getting 12.5v to the FPDM. Checked a few more grounds, all good.

And no, I only have a general use multimeter right now.
 

KRUISR

5 Year Member
Apr 16, 2015
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So just watched the video. Here are my thoughts ...

Things you have told us:
1- you can jump the fuel pump and it primes (it doesn't prime otherwise)
2- If you spray starter fluid into intake the car will start and run for a few seconds


So instead of disconnecting and moving the battery, get some appropriate sized wire (14 or 16 gauge should work - but check your wiring diagram for what gauge size currently goes to the pump). With the battery still connected for the rest of the car, create jumper wires that will reach from your jumper point for the fuel pump to the battery. Attach the two wires to the pump and get it priming and keep it priming. Now try to start/run the car. Does it run? If so, you have proved the PCM, chip and all those things will work. I would then further chase down the fuel system.
 

Mach1.0

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May 29, 2022
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Thank you for the comment.

I pulled the fuse to the ABS module, of course the ABS light came on, the car will still crank but not start.

I can only pull code P1233 with the chip installed with the key in the run position. I get “error” with the key in the ignition but not in run. I get “error”in run and key in but I’m off position with this chip removed. With chip removed, still getting 12.5v to the FPDM. Checked a few more grounds, all good.

And no, I only have a general use multimeter right now.
The FPDM and ECM communicate with each other via pin 40 on ECM (LT BLU/ORG) to pin 7 on FPDM. Do you have continuity between those two points?

Also check continuity between pin 80 ECM (WHT/RED) and pin 1 FPDM.
 

gavinmgrant

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May 23, 2022
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So just watched the video. Here are my thoughts ...

Things you have told us:
1- you can jump the fuel pump and it primes (it doesn't prime otherwise)
2- If you spray starter fluid into intake the car will start and run for a few seconds


So instead of disconnecting and moving the battery, get some appropriate sized wire (14 or 16 gauge should work - but check your wiring diagram for what gauge size currently goes to the pump). With the battery still connected for the rest of the car, create jumper wires that will reach from your jumper point for the fuel pump to the battery. Attach the two wires to the pump and get it priming and keep it priming. Now try to start/run the car. Does it run? If so, you have proved the PCM, chip and all those things will work. I would then further chase down the fuel system.
I think this is a good idea. I’ll keep you posted on this over the next day or two.
 

gavinmgrant

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May 23, 2022
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The FPDM and ECM communicate with each other via pin 40 on ECM (LT BLU/ORG) to pin 7 on FPDM. Do you have continuity between those two points?

Also check continuity between pin 80 ECM (WHT/RED) and pin 1 FPDM.
I will have to get longer leads tomorrow to shoot that section of wire. I’m constantly getting 6.97v at the FPDM connector on LT BLU/ORG from the PCM to the FPDM. 0.02v on WHT/RED, both readings with the key in run. I will shoot those stretches of wire next for any sort of high resistance or open (on WHT/RED specifically.) LT BLU/ORG obviously isn’t open since it’s carrying current, and 6.97v seems to be about right from what I’ve researched.
 

Mach1.0

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I will have to get longer leads tomorrow to shoot that section of wire. I’m constantly getting 6.97v at the FPDM connector on LT BLU/ORG from the PCM to the FPDM. 0.02v on WHT/RED, both readings with the key in run. I will shoot those stretches of wire next for any sort of high resistance or open (on WHT/RED specifically.) LT BLU/ORG obviously isn’t open since it’s carrying current, and 6.97v seems to be about right from what I’ve researched.
If you’re getting 6.97v on LT BLU/ORG then the ECM is telling the FPDM to turn off the fuel pump (see article previously sent). That voltage roughly equates to the duty cycle (i.e. 69% duty cycle). 67.5% to 82% is an off command. Why is ECM telling FPDM to shut off fuel pump? Check the fuel pressure sensor portion of fuel pump (ECM pins 62, 90, 91). Also check FRPT (ECM pins 63 & 90).
 

Mach1.0

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If you’re getting 6.97v on LT BLU/ORG then the ECM is telling the FPDM to turn off the fuel pump (see article previously sent). That voltage roughly equates to the duty cycle (i.e. 69% duty cycle). 67.5% to 82% is an off command. Why is ECM telling FPDM to shut off fuel pump? Check the fuel pressure sensor portion of fuel pump (ECM pins 62, 90, 91). Also check FRPT (ECM pins 63 & 90).
Also, while it is true that LT BLU/ORG isn’t open because you see 6.97V on it, there may be excessive resistance on it which would affect the voltage reading. It would be thorough to check from pin 40 on ECM to pin 7 on FPDM. You want to see less than 5 ohms.
You don’t need special longer DVOM leads. Use some wire as an extension to your existing leads. First take a resistance reading on the extension wire and subtract that value from your reading between pin 40 & pin 7.
 

gavinmgrant

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May 23, 2022
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If you’re getting 6.97v on LT BLU/ORG then the ECM is telling the FPDM to turn off the fuel pump (see article previously sent). That voltage roughly equates to the duty cycle (i.e. 69% duty cycle). 67.5% to 82% is an off command. Why is ECM telling FPDM to shut off fuel pump? Check the fuel pressure sensor portion of fuel pump (ECM pins 62, 90, 91). Also check FRPT (ECM pins 63 & 90).
That makes more sense once I re-read the article. So here’s some readings I took:
PCM connector side:
Pins 62, 63, 90, 91: 0v, open to ground.

So I went more downstream.

FRPT connector:
RED PINK 5v, 10,000 plus ohms to ground.
GREY RED 0v, open to ground.
BROWN WHITE 5v, 10,000 plus ohms to ground.

FRPT sensor itself: BROWN WHITE to GREY RED 1.3k ohms. All 3 pins open to ground.

I will get more wire to extend my leads to be able to shoot from the FPDM to the PCM later today from my work.
 

Mach1.0

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That makes more sense once I re-read the article. So here’s some readings I took:
PCM connector side:
Pins 62, 63, 90, 91: 0v, open to ground.

So I went more downstream.

FRPT connector:
RED PINK 5v, 10,000 plus ohms to ground.
GREY RED 0v, open to ground.
BROWN WHITE 5v, 10,000 plus ohms to ground.

FRPT sensor itself: BROWN WHITE to GREY RED 1.3k ohms. All 3 pins open to ground.

I will get more wire to extend my leads to be able to shoot from the FPDM to the PCM later today from my work.
Just for clarification, are you performing a voltage measurement and a resistance measurement? The reason I ask is because 0v to me is a voltage measurement. As a voltage measurement, 0v means there’s a short circuit or direct path for electricity to flow.
However if someone says “open to ground” I interpret that as a resistance measurement in which the black lead is on batt neg (-), the red lead is on the component being measured, and the DVOM is showing infinite resistance or “OL”.
Conversely, if “open to ground”’is referring to a voltage measurement in which the black lead is on batt neg (-), then if someone told me “open to ground” I would expect the voltage reading to be equal to B+. Not trying to be confusing, just wanna make sure I understand what you’re saying.
 

gavinmgrant

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Just for clarification, are you performing a voltage measurement and a resistance measurement? The reason I ask is because 0v to me is a voltage measurement. As a voltage measurement, 0v means there’s a short circuit or direct path for electricity to flow.
However if someone says “open to ground” I interpret that as a resistance measurement in which the black lead is on batt neg (-), the red lead is on the component being measured, and the DVOM is showing infinite resistance or “OL”.
Conversely, if “open to ground”’is referring to a voltage measurement in which the black lead is on batt neg (-), then if someone told me “open to ground” I would expect the voltage reading to be equal to B+. Not trying to be confusing, just wanna make sure I understand what you’re saying.
Sorry, I will provide clarification.

I am listing two separate readings 0v meaning my DC voltage measurement, and open to ground being my resistance measurement.

Pins 62, 63, 90, 91 should be powered by the PCM if I am interpreting the diagrams correctly, thus 0v DC being a good reading, nothing back flowing/shorted since the PCM is disconnected from its connector to take these readings. And reading open to ground, my resistance reading, is also a good reading in this case Nothing grounded or touching.

My verbiage may differ from others, so hopefully it makes more sense now.

The PCM is getting 12v DC at pin 71.

Next is to shoot/meter the entire FPDM wire pin 7 from the PCM back to the FPDM.

I have metered pins 90 and 91 previously, as they go back to the fuel pump connector. Pin 90 was getting 12v DC at the fuel pump connector, as the fuel level on the dash works fine. IIRC pin 91 was getting 1.6v at the fuel pump connector. I will re-verify that when I get the chance.
 

Mach1.0

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Sorry, I will provide clarification.

I am listing two separate readings 0v meaning my DC voltage measurement, and open to ground being my resistance measurement.

Pins 62, 63, 90, 91 should be powered by the PCM if I am interpreting the diagrams correctly, thus 0v DC being a good reading, nothing back flowing/shorted since the PCM is disconnected from its connector to take these readings. And reading open to ground, my resistance reading, is also a good reading in this case Nothing grounded or touching.

My verbiage may differ from others, so hopefully it makes more sense now.

The PCM is getting 12v DC at pin 71.

Next is to shoot/meter the entire FPDM wire pin 7 from the PCM back to the FPDM.

I have metered pins 90 and 91 previously, as they go back to the fuel pump connector. Pin 90 was getting 12v DC at the fuel pump connector, as the fuel level on the dash works fine. IIRC pin 91 was getting 1.6v at the fuel pump connector. I will re-verify that when I get the chance.
Thanks for explaining. I now understand how you’re testing.

I have the same FRPT readings you measured on the sensor and connector. So, you can rule that sensor out.

In post #32 you said BRN/WHT of FRPT connector had 5v. In post #34 you said pin 90 of ECM was getting 12v at the pump connector. The BRN/WHT at the fuel pump should be 5v. It’s going to ECM pin 90 the same as the BRN/WHT of the FRPT.

You mentioned the fuel level gauge on your dash in conjunction with ECM pin 90. If you’re looking at the wiring diagram, the variable resister inside the dashed box containing the fuel pump is not related to the fuel gauge. That sensor sits on top the fuel tank and measures pressure inside the tank.

Just a side note, when I bought my Mach it had a P1233 DTC. Wound up being ECM pin 40 bent over which I discovered when disconnecting the ECM connector to run a continuity test. I don’t think you’ll find that with your car, but with every test you’re getting closer to finding the answer.
 

gavinmgrant

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May 23, 2022
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Thanks for explaining. I now understand how you’re testing.

I have the same FRPT readings you measured on the sensor and connector. So, you can rule that sensor out.

In post #32 you said BRN/WHT of FRPT connector had 5v. In post #34 you said pin 90 of ECM was getting 12v at the pump connector. The BRN/WHT at the fuel pump should be 5v. It’s going to ECM pin 90 the same as the BRN/WHT of the FRPT.

You mentioned the fuel level gauge on your dash in conjunction with ECM pin 90. If you’re looking at the wiring diagram, the variable resister inside the dashed box containing the fuel pump is not related to the fuel gauge. That sensor sits on top the fuel tank and measures pressure inside the tank.

Just a side note, when I bought my Mach it had a P1233 DTC. Wound up being ECM pin 40 bent over which I discovered when disconnecting the ECM connector to run a continuity test. I don’t think you’ll find that with your car, but with every test you’re getting closer to finding the answer.
Thank you for the clarification on the fuel level gauge.

So I went out to the car to triple check my readings. So on the FRPT, I got 5v on BRN/WHT, and at the fuel pump connector I got 11.61v on BRN/WHT. I see where it wire ties near the throttle position sensor and goes to the fuel pump. I quadruple checked it was the correct wire I was shooting. 11.61v at the fuel pump on BRN/WHT.

I found a YouTube video that *kind of* shows the same reading, he’s not very specific on what pin but he does say “first pin” which is where my brown white is on the fuel pump connector as well. I’ll link it and you can take a look.


View: https://youtu.be/E7aViENbOeQ


I didn’t notice any pins bent or burnt on the PCM when I’ve checked previously but I will check again. I’ll check the connector side as well for any signs of damage on the pin 40. With 6.9v on LT BLU/ORG, it’s making connection. So I’m suspecting nothing wrong with the actual connection, but I’ll double verify tomorrow.
 

gavinmgrant

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May 23, 2022
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Thanks for explaining. I now understand how you’re testing.

I have the same FRPT readings you measured on the sensor and connector. So, you can rule that sensor out.

In post #32 you said BRN/WHT of FRPT connector had 5v. In post #34 you said pin 90 of ECM was getting 12v at the pump connector. The BRN/WHT at the fuel pump should be 5v. It’s going to ECM pin 90 the same as the BRN/WHT of the FRPT.

You mentioned the fuel level gauge on your dash in conjunction with ECM pin 90. If you’re looking at the wiring diagram, the variable resister inside the dashed box containing the fuel pump is not related to the fuel gauge. That sensor sits on top the fuel tank and measures pressure inside the tank.

Just a side note, when I bought my Mach it had a P1233 DTC. Wound up being ECM pin 40 bent over which I discovered when disconnecting the ECM connector to run a continuity test. I don’t think you’ll find that with your car, but with every test you’re getting closer to finding the answer.
I tried something before I went to work today. So I had a PCM sitting around from a 2004 GT 4.6 2v. So I took the PCM out of the Mach 1, shot power at LT BLUE ORG of the FPDM, of course got 0v. Good. Then shot resistance from LT BLUE ORG to ground with the PCM re-plugged in. Got about 20,000 ohms. Moved on. So I installed the PCM from the 2004 GT into the Mach. Got 6.99v, sometimes went up to 7v, at LT BLUE ORG on the FPDM. So something is causing the computer to do that. So at this point I think I’m going to rule out the PCM unless you have anything else I should try.
 

gavinmgrant

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I tried something before I went to work today. So I had a PCM sitting around from a 2004 GT 4.6 2v. So I took the PCM out of the Mach 1, shot power at LT BLUE ORG of the FPDM, of course got 0v. Good. Then shot resistance from LT BLUE ORG to ground with the PCM re-plugged in. Got about 20,000 ohms. Moved on. So I installed the PCM from the 2004 GT into the Mach. Got 6.99v, sometimes went up to 7v, at LT BLUE ORG on the FPDM. So something is causing the computer to do that. So at this point I think I’m going to rule out the PCM unless you have anything else I should try.
I knew it wouldn’t start with a different computer in it, but I just wanted to see what would happen with the voltage on LT BLUE ORG.
 

Mach1.0

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I knew it wouldn’t start with a different computer in it, but I just wanted to see what would happen with the voltage on LT BLUE
Hey, got in from work and checked, I got 5v on the BRN/WHT at the pump like the diagram shows.
B9F110FC-D4A1-4FBD-8E35-49136927D620.jpeg
Let’s find how the 11.61v is getting on your BRN/WHT.
 

Mach1.0

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Hey, got in from work and checked, I got 5v on the BRN/WHT at the pump like the diagram shows. Let’s find how the 11.61v is getting on your BRN/WHT.
Since the no start problem started after you drove into your garage, the cause is likely related to the work done thereafter. During the battery relocation a wire carrying 12v was possibly pierced and shorted to the 5v circuit.
Maybe this method will isolate things: Set DVOM to DC volts, put the black lead on batt (-), red lead on BRN/WHT of fuel pump connector (use hooded alligator clip for that pin, or with connector separated backprobe BRN/WHT. Get a helper to start pulling fuses until the 11.61v becomes 5v. That will identify which circuit is shorting to your BRN/WHT circuit. Things to look at are fasteners added which can pierce wires behind panels/bulkheads and pinch points on new wires ran. Let us know what you find.