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Cluster/ECU issues after racecar conversion

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captdistraction

GrumpyRacer
1,954
1,698
Phoenix, Az
Since converting my car to full race-tarded, I've ran into one major issue (long warning):

I can't get the cluster to talk to the PCM and/or start the motor due to this issue. On power up of the car, all the relays audibly trigger and everything appears to be getting voltage (probed all the fuses and all appear fine). Key in on the ignition reveals a number of faults in the cluster:

ABS system fault, Check Advancetrac, Passenger door open (I have the sensor unplugged), check charging system, fuel level low (though the gauge reflects 3/4 tank after I filled it with new fuel) and some others. After clearing those with the reset button the mileage is not shown on the dash, just zeros with a rapid flashing key indicator. No engagement of starter occurs however, I can move the throttle plate around (suggesting the PCM is at least powered up).

Some searching means that either A) the cluster can't talk to the PCM and/or other modules on the CAN network, B) the PCM isn't powered up or is faulted, C) the cluster is faulted, D) a PATs issue with the key (though the key has power, the fob does function still and I left the transceivers in).

So working from that knowledge I started troubleshooting:

Scenario A: Cluster cannot see/talk to the PCM
I did briefly see the mileage, and that suggests to me a issue on the HS-CAN bus itself.
Plugging in a XCAL3 went nowhere, it cannot read anything from OBD2 connector, though does power up
I believe PCM is working as the throttle plate is moving based on pedal input.

I may have an issue in the dash harness, as I had trimmed a number of the systems out of it (audio/NAV) and I know I made at least one mistake in connector (the headlight switch connector). That being the case, my other work becomes suspect, so I've ordered a new base model harness which I will install unmodified and will test on Friday.

I've also verified the grounds throughout and all seem to be ok as well.

Another thought is CAN termination, I've removed the following modules:
sunload sensor, HVAC module, GPSM module, FDIM module, ACM Module, FCIM Module, APIM Module, clockspring and all audio hardware.

I did keep the restraints control module, side impact sensors and the rear passenger side body module (I'm not sure of its name).

On the dash harness I had carefully (or so I thought) depin the unneeded connectors). On the body harness I removed only the seat subsections and trimmed off the antenna lines.

Scenario B: Cluster not powered up or faulted

The PCM connectors were exposed to air for 15 months without power or their plugs. I'm not sure if any of that is a factor, the connectors appear weathersealed and the contacts themselves are not tarnished in a manner I'd be worried about. However its a possibility.

Scenario C: the cluster is faulted

Possible I guess, not sure how that could have happened or if prolonged disconnect means reprogramming of some sort

Scenario D: Pats-hole

I've checked the connectors, but is still on the same questionable harness. Disconnecting and reconnecting battery or the pats tranceiver makes no difference in behaviour.


Outside replacing this questionable dash harness, I'm at a loss. Not sure what my recourse is if I can't get this figured out, maybe a Ford Dealer visit or start considering abandoning all the wiring for a controls pack (which would be a huge pain in the ass from a labor standpoint and loss of functionality versus the factory wiring).

Anyone have thoughts? I'm leaning towards A and my modified dash harness being the culprit for now, but I can't claim to really understand automotive networks and control systems.
 
It sounds like a PATS issue, do you have a tune? If so make sure PATS is turned off in the tune and started should turn over
 
380
2
I can't provide alot of help on this, but here's just a few thoughts I have.

I would tend to rule out option B. Scrap yards will keep clusters hanging around on a shelf for a long time. If you lived off the beach in Florida, I'd be worried about it but your climate is so dry that I think you'd be fine there.

I also don't think you'd need reprogramming in option C. It might be faulty, but whatever solid state memory is in there should be pretty stable. Might want to just ask a service dept employee without bringing the car in just to see what he says. I've had pretty good luck with weird questions by asking the guys that work on the cars, not so much with the service manager.

I think option A or D are most likely, or option C with the cluster being faulty. The new harness on Friday will tell you alot.
 

302 Hi Pro

Boss 302 - Racing Legend to Modern Muscle Car
2,009
441
Southeast
Nice to see you found the problem and fixed your communications problem. That Instrument Cluster wiring harness is a mass of tightly bound wiring as it comes up to the back of the Insturment Panel connector.

Car sounds great in your build thread.

When do you plan on getting her out on the track for her shake down run?

All the best,
302 Hi Pro
 

captdistraction

GrumpyRacer
1,954
1,698
Phoenix, Az
F.D. Sako said:
Is that an easy fix, or a headache wire splicing?

I just bought a base model harness. In all fairness, my modified harness only saved a couple pounds.

So the advise I have is leave it all alone, just ziptie it all together, a race car conversion leaves more than half the car's very many plugs unused, however there's many common grounds, circuits and data paths where removing one item could come back to haunt.

I still have a ways to go for testing, hoping to make the car driveable today if I can find a upper radiator hose.
 

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