Joe V

I decide to start a new thread instead of clogging up Ouchman’s Cheap TPS Fix thread.

Original Symptoms: No OD, No Speedo, No Charging, No AC, No Wait To Start light, No Water In Fuel light.

Did the Ouchman TPS by-pass with POT thing: No improvement.

Did the Crank Positioning Sensor thing: Removed CPS and cleaned all the crud off of it, check wires – looked good, cleaned the crank damper, put the sensor back on and gapped it to 0.050 w/brass feeler gauge. No improvement

New Added Symptoms: Wait To Start light comes on after starting vehicle. Vehicle did not start twice after cranking (truck has always started instantly after turning key with a 1 second maximum wait time).

Did the PCM plug check thing: Pulled plug, inspected, looked good, cleaned anyway. No Improvement.

Did the AC PCM relay swap thing: No improvement.

My next step is to by-pass the PCM Voltage Regulator with an external VR and hot wire the AC.

Question…If this doesn’t work, should I:
A. Purchase a second VR because I fried the 1st one.
B. Purchase a new Crank Positioning Sensor (Speed Position Sensor).
C. Purchase a new PCM.


This has been going on for a few weeks now. I’m determined to fix this by the end of the month, because in 3 weeks I’m going on a 1,100 mile trip w/6,500lbs connected to the hitch.

Did I mention I also have a VW TDI that I need to work on next?


Thanks,

Joe V

Boatnik

My uneducated guess fits Murphy's Law. Replace the PCM. In my opinon there is too much wrong at one time to be anything else.

flashgordon

I will have to 2nt that. You have dun enuff checking and cleaning. Time to compute(PCM)

wannadiesel

Before you condemn the PCM, do a little checking at the main connector. With the key off you should have 12 volts at cavity 3, ground at cavities 11 and 12. With the key on you should have 12 volts at cavity 9. If all this checks out, then replace the PCM.

When you pull the PCM connector off, consider the top to be the side without the tabs. Looking at it from the PCM end, cavity 1 is in the upper left corner. Just count across that top row to find the right hole to probe. It's OK to check this stuff with a test light since the PCM is unplugged.

Joe V

Since my battery is at 10.8v right now the corresponding cavities are measuring between 10.8v & 10.3v. So I decided to call my local Napa to see if they had a PCM in stock, the guy on the phone quoted me 1 week lead at $295+tax...I then picked the phone back up off the floor and asked him for a VR regulator price; in stock at $25. I then called AZ they have em in stock for $19.

So I'm going to try the VR bypass thing.

Here is some stuff I picked up from other threads and combined them onto on page that I printed out:

"The voltage regulator on the 92-92 trucks is an internal unit inside the control module. If this goes out, you can mount an external voltage regulator like the earlier first gens used."

The two terminals on the alternator for the regulator are interchangable.
The alternator is a dumb alternator for an external regulator.
The PCM is that regulator normally.
The alternator does not care weather it is controlled by the PCM or a regulator.
The PCM is not affected by not being hooked to the alternator.

*The two terminal regulator has the contacts in the shape of a pyrimid.
One terminal is missing. The missing terminal and one other terminal are at the base of the pyrimid.

**Ok, hook the two alternator terminals to the two regulator terminals.
Does no matter which goes to which. Now run a 12 volt line from an ignition source to the top regulator terminal along with the alternator wire. The terminals for the regulator can be just the round female terminals that are used for connecters on lights and other places or go to an older junk yard and cut the plug from about any old chrysler product.

***Important: disconnect the wires that go from the alternator to the PCM,
you need to disconnect the wires that go to the pcm that you are now connecting the VR

That's it except you need a good ground from the alternator to the regulator case. "

*Ok, here's a good pic of the VR


**I'm assuming the two terminals with one above the other are the correct ones.


***Which cavities are for the alternator? I can cut the wires on the back of the plug.


Thanks,
Joe V

mhuppertz

Don't worry about the connector, just use new wires and terminal lugs on the alternator. That way your can change it back if you ever want to, and you might, because the older style regualtor tends to pulse which shows up in the headlights at idle.

I did this, and put ir back after I figured out one os the wires coming from the CPS was intermittently open.

wannadiesel

You had good grounds at 11 and 12? PCM must be toast, like Boatnik and flashgordon said there is too much wrong at once.

Do what Mark said to get it charging, don't hack the harness. If you are never going to replace the PCM, you will need to install a mystery switch for the OD and a relay to run the A/C.

Joe V

Well I went ahead and bought a reman PCM which cured the problems. For future reference I boufght it here for $161 + $20 (3 day UPS shipping) + $70 core deposit.

M & S Express
36 Jensen Road
Watertown, MA 02472
1-781-810-4507

http://www.autopart.com/ecc/ECC1992DODGEW250PICKUP.htm


Thanks,

JOE

wannadiesel

Glad you got it working. It's no big deal to bypass the voltage regulator if that's the only problem. When the whole PCM is fried you really can't work around it.