2004 Mach 1 crank but no start. dying inside

gavinmgrant

Member
May 23, 2022
35
3
8
26
Texas
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.
 
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gavinmgrant

Member
May 23, 2022
35
3
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Texas
I forgot to mention the only DTC code my cheap code reader pulled was P1233 for FPDM offline. Bought a brand new one, no change just to rule it out.
 

gavinmgrant

Member
May 23, 2022
35
3
8
26
Texas
UPDATE: visually examined the PCM and discovered there was a Bama 4-Bank Eliminator Chip installed in the PCM. I searched the part number and it’s the same one on the American muscle website that specifically says not compatible on the 2004 Mach 1. The previous owner must have installed it, because I sure as hell didn’t. Anyways, I took the chip out and put the key in the run position. The odometer shows dashes and the IAC valve is making a loud buzzing noise all of the sudden. I disconnected the IAC valve and it stopped so I know it’s that. Still cranks but doesn’t start. What in the world would cause the removal of the chip to start making the IAC valve buzz? And the odometer to show dashes? I’ve checked all of my fuses 5 or 6 times but I will check again tomorrow just to be sure nothing happened when I tried to start it after removing the chip. With the chip removed, wouldn’t the PCM revert back to stock tune? I would like to think it would but I’m not sure. Someone fill me in here. But, with the odometer showing dashes now I’m thinking it’s an absolutely fried PCM.
 

COramprat

...I can take it. I think.
Mod Dude
Mar 2, 2003
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If it was running with the chip then I'd eliminate that as the suspect, compatible or not. The chip should have one of the positions as the stock tune. I'm not completely sure but I think all of the info for the PCM is on the chip now.
I'd go back to the shorting of the battery cable. Somewhere in the reroute and issues thereafter is your problem. My experience has been to always go back to any new changes when you experience problems. From what I gather your problems started at the bus bar install. I'd start there. Maybe remove it and go back to what was there intitially.
 

gavinmgrant

Member
May 23, 2022
35
3
8
26
Texas
If it was running with the chip then I'd eliminate that as the suspect, compatible or not. The chip should have one of the positions as the stock tune. I'm not completely sure but I think all of the info for the PCM is on the chip now.
I'd go back to the shorting of the battery cable. Somewhere in the reroute and issues thereafter is your problem. My experience has been to always go back to any new changes when you experience problems. From what I gather your problems started at the bus bar install. I'd start there. Maybe remove it and go back to what was there intitially.
So the way the previous owner had the battery cable routed was from the trunk, underneath the car, and straight to the starter. So it was in a vulnerable position being routed under the car. Then a wire went from the starter to the fuse box, which had the stock wire from the alternator to the fuse box. When I rewired most of the charging system, I didn't change the actual path of current. My reroute goes battery power wire in trunk (ground also in the trunk) through the cabin to bus bar terminal 1, starter on bus bar terminal 2, fuse box to bus bar terminal 3, then alternator to fuse box. Fusible link still in use on the fuse box. I get 12v where I need to, and grounds are good. The only place I am consistently not getting 12v, is to the fuel pump. With the chip in or out.
 

gavinmgrant

Member
May 23, 2022
35
3
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26
Texas
If it was running with the chip then I'd eliminate that as the suspect, compatible or not. The chip should have one of the positions as the stock tune. I'm not completely sure but I think all of the info for the PCM is on the chip now.
I'd go back to the shorting of the battery cable. Somewhere in the reroute and issues thereafter is your problem. My experience has been to always go back to any new changes when you experience problems. From what I gather your problems started at the bus bar install. I'd start there. Maybe remove it and go back to what was there intitially.
Someone else mentioned the stock tune position on the chip as well. But my chip does not have a selector switch like I have seen on other chips. There was a harness with 3 wires POORLY spliced/wrapped around other wires on the PCM harness that went to nothing. I found it still spliced to the PCM harness and the 3 wires just went under the carpet... So I have a feeling that was part of the selector switch at one point. The PCM wires used in that mystery harness have been repaired since then.
 

COramprat

...I can take it. I think.
Mod Dude
Mar 2, 2003
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Oh wow. So it was basically disconnected. The wires ended under the carpet?

It's obvious you lost power to the fuel pump. I'm thinking now it's at the PCM. Something isn't connected correctly there. The odometer dashes and the code kind of makes me think that you've lost connectivity somewhere. I'd rule out all wiring issues before replacing the PCM. Sometimes the second or third go through you will find it.
 

gavinmgrant

Member
May 23, 2022
35
3
8
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Texas
Oh wow. So it was basically disconnected. The wires ended under the carpet?

It's obvious you lost power to the fuel pump. I'm thinking now it's at the PCM. Something isn't connected correctly there. The odometer dashes and the code kind of makes me think that you've lost connectivity somewhere. I'd rule out all wiring issues before replacing the PCM. Sometimes the second or third go through you will find it.
I'd send you a video of it if I could. Someone else showed me a picture of a selector switch for a chip and the harness looks very similar. Both 3 wires tapped into the PCM harness. The wires were under the carpet because it looked like someone just put them there to be out of the way. I find very bizarre things on this car everyday. I'll go through the wiring again but everything has been clean so far. I really think it's a PCM problem. Either it needs to be replace or it needs to be flashed back to stock. Or something along those lines. CCRM is sending power to the FPDM, but the signal to provide power or a ground to the fuel pump isn't there. So on PINK BLACK on the FPDM I get 12v. On LIGHT BLUE ORANGE I get 6.97v, on WHITE RED I get 0.02v. I have depinned the BROWN PINK wire that goes straight to the fuel pump from the FPDM, probed the FPDM output and I consistently get 1.8v in the RUN position. So I believe something in the PCM is not telling the FPDM to activate the fuel pump.
 

gavinmgrant

Member
May 23, 2022
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The thing is it worked before the incident loading it. Did you check the connection going back to the fuel pump?
yes. I shot the wires from the FPDM to the pump connector. All good there. I took the harness apart and verified no breaks or chaffing. And the fuel pump is also brand new.
 

COramprat

...I can take it. I think.
Mod Dude
Mar 2, 2003
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Let's work on the original issue. You shorted the battery cable but once you taped it up, it worked fine. There now is a multitude of other things in play now. The rewire of the battery, the removal of the chip and the installation of the bus. I want to say that the bus is where the problem lies. So let's go to the fuel pump. Can you jump it to make sure it is funtional?
 

gavinmgrant

Member
May 23, 2022
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Texas
Let's work on the original issue. You shorted the battery cable but once you taped it up, it worked fine. There now is a multitude of other things in play now. The rewire of the battery, the removal of the chip and the installation of the bus. I want to say that the bus is where the problem lies. So let's go to the fuel pump. Can you jump it to make sure it is funtional?
I have jumped the pump directly to 12v (I removed the battery from the car to do this) and it runs.
 
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KRUISR

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Apr 16, 2015
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If you jump the fuel pump on, will the car run?

Pics or video of bus bar, battery install, etc always help. Posting a video here, simply make the video, upload to Youtube and copy the link into you post.
 
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gavinmgrant

Member
May 23, 2022
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Texas
If you jump the fuel pump on, will the car run?

Pics or video of bus bar, battery install, etc always help. Posting a video here, simply make the video, upload to Youtube and copy the link into you post.

View: https://youtu.be/qjR4vVdI8lE


Here you guys go. I say “I’m getting power everywhere I need to” besides the fuel pump of course. I mean that in regards to the fuses and PCM. I forgot to mention in the video the odometer shows dashes without the chip installed.