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FishPlug · 01-28-2022, 05:23 PM

I have a postal service surplus 2003 Workhorse P42 with 6.5 GM diesel and 4L80 trans. Won't shift out of 1st. No Speedometer, no odometer, ABS light. Replaced both speed sensors. Checked fuses. Starts and runs great. Two repair shops couldn't pull OBD codes. Lots more boring details, but any advice?

Ultra RV Products · 01-28-2022, 07:00 PM

Sounds like a failed DRAC module. I would contact these guys: https://udmodule.com

FishPlug · 01-29-2022, 06:32 AM

Thanks. Ill check into the DRAC

Soppy · 01-29-2022, 06:59 AM

If you can't pull the codes , you have a communication problem . The problem could be the PCM or the ECM and TCM modules depending on your configuration. I would start by checking the connectors.

FishPlug · 01-29-2022, 02:00 PM

Will do. No lack of connectors on this rig. Thankfully the P42 service manual has already been posted on IRV2. Chapter 6 - Engines is 5,004 pages. No excuses for troubleshooting the problem.

FishPlug · 02-03-2022, 02:35 PM

No idea what PCM, ECM or TCM look like. I don't see any loose connectors anywhere. My hazard lights don't work either.
Attached an OBD2 and got PO113 - intake air temperature Sensor 1 Circuit High Input. Doesn't seem to relate to my stuck transmission.
Also, can't seem to attach pictures to these posts.

catmandoo62 · 02-04-2022, 08:53 AM

that intake air temp could prevent it from locking up the converter,but shouldn't bother on the gears.the ecm will be an aluminum looking box about an inch and a half thick and about 8 inch square with 2 or 3 big harnesses into it on one side,might by under the engine cover right behind the radiator,my 99 winnie is on a bracket in front of and above the drivers side valve cover.do your turn signals work?if so you could just have a bad flasher on the 4 ways.

FishPlug · 02-20-2022, 09:36 AM

All the connections to PCM, TCM etc. appear fine. Disconnected, sprayed contact cleaner and reconnected, but no change. May throw a few parts at the problem - ABS module is what one mechanic predicted. DRAC unit has been mentioned. PCM? Months ago I did have a dragging front caliper and rotor that got red hot. Replaced the caliper and all good, but maybe the heat damaged the wheel speed sensor for the ABS. The wheel speed sensor seems to be built into the the wheel spindle, not accessible externally. I think it would show on OBD-2 scan, but no OBD scan works, so back to the likely computer problem.

FishPlug · 10-07-2022, 03:45 PM

Had the DRAC unit replaced and truck now shifts through all the gears, but runs rough, rolls black smoke, revs oddly and doesn't respond to the accelerator properly. No more warning lights on the dash. OBD2 still unresponsive and get no codes. Can't drive it for work. Probably electronic related, but don't know any mechanics who work without OBD and codes.

FishPlug · 11-13-2022, 03:21 PM

Engine will start, but idles at 1500 rpm and rough. Seems like an injector may be clogged. Barely touching the accelerator can send the rpm to 3500 or even higher and I have to panic and shut the motor down. Rolls tons of black smoke. Don't know if the transmission shifts because can't touch the accelerator to build speed because tons of black smoke and engine revs too high. Total mess of a motor!! OBD2 reports no codes. OBD2 doesn't provide any usable data.

D Gardiner · 11-13-2022, 03:38 PM

Odd problem after replacing the DRAC. My guess is something got unplugged.
It could be a CTS, (coolant temp. sensor). If yours has a MAF (mass air flow) sensor, it might do the same.

edgray · 11-13-2022, 07:18 PM

May be wrong, but I’m thinking the Linear Logic SG II is for gasoline only. I think they make a similar unit for Diesel. Scan gauge D or something like that.

1972VWbus · 11-14-2022, 06:05 AM

Quote:

Originally Posted by FishPlug

Engine will start, but idles at 1500 rpm and rough. Seems like an injector may be clogged. Barely touching the accelerator can send the rpm to 3500 or even higher and I have to panic and shut the motor down. Rolls tons of black smoke. Don't know if the transmission shifts because can't touch the accelerator to build speed because tons of black smoke and engine revs too high. Total mess of a motor!! OBD2 reports no codes. OBD2 doesn't provide any usable data.

Black smoke = excessive fuel

You have a scan gauge? If so what does the coolant temp say when cold vs hot?

FishPlug · 11-20-2022, 11:08 AM

I started the engine and coolant temp said 85 degrees then increased to 100 degrees in about 5 or so minutes. I think the temperature is ok. Waiting on a new PMD (pump mounted driver) to arrive in a couple days. Replaced it 2 years ago. Maybe time for a new one. Hope it works or it's probably clogged or failed injector.