Engine Control Modulator
 

any way to test a engine control modulator? voltage regulator went out and fried radio, delay wipers, lost several other items as well, such as od, cruise, grid heater, all controlled by the ecm
this is a 91.5 12v with an auto trans, thanks++++

Hot Wrench, eh. Would help if you knew the nomenclature of the trade.

These things don't have an engine control module. It's called a <P>owertrain <C>ontrol <M>odule.

Anyway, you may have lost the ground to the PCM. With luck, and that ground repaired, it might work. I'm pretty sure it overcharged for awhile before that much damage was done.

Or, you might have lost a fusible link and nothing is damaged but the link.

It would take hands on, an elementary knowledge of electricity, and a factory service manual to get to the bottom of it.

You might need to take it to a repair shop.[tapdshut]

Geezus, the condescension is as thick as mosquitos in July...Hotwrench, meet Hothead. [coffee]

[laugh]

its not a fusible link, Sticky gives a test for a computer on later model first gens, thought someone might have a test for the early model unit

Hope you don't mind a little help from HotHead.[roll]
It's interesting when a little good natured jab offends someone uninvolved.

I have a Chrysler publication 81-699-0310 5.9L 1993 Cummins Diesel Truck Powertrain Diagnostic Procedures that covers the formal analysis of the PCM, sensors and controls.

Electronically, it's pretty elementary. The information you need is in the wiring diagrams. I believe there's a link to a set (1993 would work) in the FAQ's.

To start with, power (at 2 places) and ground at the PCM, and then power from PCM to the CPS, and signal back to the PCM should light it up. If it then doesn't field the alternator, it's dead. Pinouts, color codes, and voltages are all in the electrical diagrams.

Most of the problems with this system are grounds and dirty connectors.

hope it helps.

thanks for the info, pretty sure its burnt, one of the guys pulled the pos cable off while it was running and putting out over 18volts, thats when it poped my radio, after that I had no cruise, no od, no grid heater or wait light, I read all these were controlled by the pcm, I tested out the ignition switch, fuse box and fuse links, all good, will try to do a little testing on the pcm before I buy a replacement

He's lucky he didn't blow his head off making sparks near an overcharging battery. He's dangerous. Keep him away.

Fully fielded and not loaded into a battery, that alternator can put out 50 - 100 volts. I suspect you're right on the fried PCM.

When you put in another one, check the field wire between the PCM and the alternator to be sure it isn't grounded. That would have been the original, (and only) fault before the battery was disconnected.