--------------------------------------------------------------------------------

well, i pulled the engine wire harness off the truck to sheild the TPS wire and Trans solenoid control harness. i made sure everything was put together right before taping the harness back up and reinstalling it. everything is plugged in except a check connector by the grounding point at the front of the block, 1st cylinder and a 2 wire black connector that comes out of the harness with the Fuel solenoid conn and intake air temp. this is the only connector im worried about cuz i cant find ANYTHING in this area to plug it into.

but my truck doesnt give me any of the warning lights when i go to start, nothing. then when i start it, my voltage doesnt move from 12.4-12.5v. also, my Tach is dead, my Speedo is Dead and the transmission only has mechanical function, no electronic function. i have no 1st gear, 4th gear or lockup. i only have reverse, 2nd and 3rd. putting the truck in drive means its IN DRIVE, no automatic shifting. if i put the truck in 2nd, its in SECOND, no shifting from 1 to 2. Putting it in 1st leaves me with 2nd.

the ONLY thing i fiddled with was the engine harness to sheild those wires and thats it. i dont understand how R&R of my engine harness can cause my PCM to die like this.

i also got my alternator brushes replaced for $21 while i was at it. i thought my charging problem and electrical gremlins were caused by this, but nothing has changed.

one last thing, i disconnected the alternator charge cable from the alt to test that i had same voltage at the alt as the batteries. while the cable was off, i bumped it and it arced against the turbo inlet. did i pop a breaker that should be reset or what?
help... i need my baby to tow a car to jacksonville!

 

There is a large fuse in the underhood fuse box. I think it is 150 amp. red and bolts in. That could be the no charge problem- a lot of people also blow these while using an oil filter wrench removing the filter. Look there. Also look for blown fuses with the gauges and such problem. I think the gauge fuse also feeds the trans solenoids. Remeber there is an inside fuse box to check too.

 

As you probably already know all of the problems you are describing have one thing in common, The PCM, I have read many times that most problems are not the PCM but something that it needs to read before it will work all the gauges and the charging system. Look for the power to the PCM or maybe you had a plug come loose while you were working on the harness. I think I would take the harness loose again and look for a plug that is not together tight. I would also take a meter and test all the fuses in the main panel under the hood, just because it looks good doesn't always mean it is. I have found several fuses that look good but were not. Good luck electrical problems are not fun.

Dieseltim

 

i tested all the fuses and they cam back 0.5ohms resistance, both under the hood and in the passenger compartment. i have continuity from the positive batt terminal to the black cable that leaves the fuse box under the hood.

the PCM has to be getting power since its sending power to the CPS plug. if the PCM is getting power and sending power, i would think that means the PCM is actually turning on, right?

just to clarify, i REMOVED the entire engine harness from the vehicle and then reinstalled it. i plugged in every connector on the harness EXCEPT the check connector by the front engine ground point, a black 2 pin connector by the Fuel shutdown solenoid plug, and a plug just above the trans dipstick near the AC drier/receiver plug.

i unpinned the TPS signal wire from the PCM connector, (driver side conn of the 3) to sheild it. there was also a larger wire, black/red or black/orange which came loose as well. once i reassembled the driverside conn and replaced the TPS pin, i looked at the PCM side of the plug and all the pins appeared to fully inserted in the connector.

itd be strange that the PCM failed while the truck was sitting with the engine harness uninstalled. people seem to think the PCM is a robust item.

 

97 in your sig I presume....

Not sure what you are refering to when you say "CPS plug".

No charging, dead tach, loss of electronic trans features would lead me to check out the Engine Speed Sensor circuit. JTEC uses that input to know when the engine is running.......of course it could be a mirad of things since the harness was out.

 

CPS= crank position sensor.

these trucks are too new to suffer from heat embrittlement on the plugs and sheathing. the only problematic areas are the fiber tape that was used on several spliced areas of the harness. i pulled my harness apart to find that a white/orange wire that had a crimp splice on it had deteriorated and was fully exposed to the rest of the wires. had this gone unchecked, the sharp edges of the crimp would have abraded thru the jacket of adjacent wires and caused an undetectable electrical fault.

simply R&R of the engine harness will not cause problems if done right. i do engine harness modification, splicing, lengthening and conversions for Toyota supras; im used to this work.

as i mentioned above, im getting 12 volts on pins where i shouldnt. so either the common 5vdc supply circuit for all the 5vdc sensors is shorting internally to a 12vdc wire, or i have a dead capacitor/resistor which isnt regulating the voltage at 5vdc for the sensors. so far, my crank sensor wires are 100% intact from the plug to the PCM connectors. if i cant find a fault in the harness anywhere, im going to go into my PCM and look for electrolytic leakage from the capacitors, burned/corroded traces or other issues.

EDIT: the harness checks out to be A-OK. theres zero continuity between any of the 3 wires. the common 5vdc power supply and common ground are all intact with no apparant abrasions, hot spots, melting or exposed center conductor. the gray/black signal wire to the PCM is also intact w/ no obvious faults. there is only 0.6ohms of resistance between the sensor plug and PCM plug on all 3 wires. its looking more and more like my PCM is faulty, not the wiring or sensor. where can i have mine refurbished and will it be cheaper than a new one from rockauto.com or whoever sells the PCM for ~$200?

 

Sounds to me like a bad ground. Put a small load (1K resistor) from the pins you shouldn't see the 12V on to ground and see if the voltage changes.

 

ive gone through all my grounds. the passenger side ground cable is new and the block i cleaned w/ brake cleaner and sand paper. the driverside ground cable is new too. i cleaned the block and ring terminal w/ brake cleaner and sand paper, as well as the 2 ring terminals on the engine harness itself. i also added an 8AWG fine stranded ground cable from the PCM case to the negative battery cable.

my grounds are fine unless there are other grounds besides the ones i know about?