CaptDistraction

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: PCM 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 *** 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.

LEXiiON

Sounds like the HS-CAN connection to the PCM is not available. You need to be able to connect from the ODB to the PCM and if the cluster cannot talk to the PCM through HS-CAN you get all the weird stuff..
Check HS-CAN from the ODB to the PCM. You will find the pinout in the wiring diagrams. Had the same issue with our EcoStang build, but was resolved doing this.
LEXiiON

CaptDistraction

I'll check that out. I do have the hs can specs and can try reading the voltage on the bus

LEXiiON

Just use a Ohm Meter and check from the OBD to the PINs on the PCM... See if it beeps.

LEXiiON

5.M0NSTER

Could it be lack of termination? The last unit usually has 120ohm termination, if you trimmed that unit out you may have lost termination and have to add a 120ohm resistor at the end of the bus between CAN hi and CAN low wires.

CaptDistraction

Resolved. Bad dash harness. Thanks!

5.M0NSTER

Sweet, glad you were able to diagnose it!