jcb

If the voltage regulator goes out what else will not work ? 1992 d350 diesel.

wannadiesel

The voltage regulator is in the PCM on your truck. It needs to see a signal from the crank sensor or the voltage regulator will stay off, and you will have no A/C or OD. Check the crank sensor and wiring. If everything else works, try swapping the front and rear relays on the driver's side fender. The front one is the field relay for the alt that the PCM runs, rear one is A/C clutch. They are identical, so swap them and see if you start charging.

jcb

Just tried the flip nothing.the heater grid is not working also

wannadiesel

Check out the crank sensor, most of the time it's torn up wires that are the problem.

jcb

The wires seem to be ok. How do you check the crank sensor ?

jcb

replaced crank sensor still no a/c,tach,or charge

wannadiesel

What's the air gap between the sensor and the damper? Should be 0.050", check it with a brass or plastic feeler.

R C Cola

Unplug the voltage regulator on mine and the voltage goes down to 12.9v
I have been told that it can malfunction and allow the full 16v to get to the battery. Question mine is 91.5 w/remote regulator (firewall), Do I have a " Crank Sensor " on my truck. R C

wannadiesel

RC, no your truck does not have a crank sensor. That's a '92 and up thing.

jcb

Checks out good

MBolivar

JCB,

I had those symptoms last year sometime. In the end it was a bad PCM. Took less than 10 minutes to R&R but, set me back 200 some odd dollars. I bought mine online.

wannadiesel

Yep, it's starting to sound that way. Before you condemn the PCM, unplug it and look at the connectors to see if there's a bunch of corrosion.

jcb

can I mount an external voltage regulator like the earlier first gens used ? Would the whole ECM be bad? The plug looks nice.

wannadiesel

Yes, guys have switched to the old regulator and hot wired the A/C compressor.

MBolivar

JCB,

Look in the 'Tech Facts' section. There's a run down on installing an external voltage regulator. They're waaaay cheaper than a PCM.