I have a 92 cummins , that isnt charging and is only showing 12.3 volts .it wont shift into overdrive . also isnt reading speeds . I have replace the chank shaft sensener and that didnt seem to do much of anything .

Do the key trick... Turn the key on off on off on... Watch the check engine light and count the flashes should be in 2 digit groups.

Do the key trick... Turn the key on off on off on... Watch the check engine light and count the flashes should be in 2 digit groups.

On a '92? Isnt that OBD1? Or do they display codes like that, as well?

On a '92? Isnt that OBD1? Or do they display codes like that, as well?

I'm pretty sure that the key trick doesn't work for any 1st gens, I know it doesn't work on my Dads 91.

crank position sensor was my first thought.... does it register RPM on the tach?I believe for OBD-1 you'll need to ground a specific pin in the connector, and while grounded it will do the CEL flash. I don't know which pin off the top of my head.

OBD I instructions:

The Quick Paper Clip Test

Since we are looking at the connector pins, it should be mentioned here that a quick method to see which trouble code or codes are being set in your cars ECM is to jumper the A and B pins of the 12 pin ALDL OBD1 connector with a paper clip. While the car is off, sitting still, turn the ignition key forward while this jumper is in place. Do not start the car. The Service Engine Soon ( SES ) light will flash in a repeating sequence, telling which trouble codes have been set in the ECM. A service manual for your year car will have a chart outlining what each trouble code stands for, or this Trouble Code website can be of help. This paper clip method will tell you the trouble code or codes set in your ECM, but it will not tell you what conditions the trouble code is being set under, or let you clear the trouble codes on the fly.

I have a 92 cummins , that isnt charging and is only showing 12.3 volts . it wont shift into overdrive . also isnt reading speeds . I have replace the chank shaft sensener and that didnt seem to do much of anything .

My 91 had the same issues about 2 days before the pcm caught fire and destroyed my wiring harness. :banghead:

You have a problem with your pcm which controls all of your listed issues. I found a company on ebay that I am thinking about sending my pcm for a rebuild. All of the first generation pcm's seem to be going out these days. Make sure that you do not have a corrosion issue due to the close proximity of the battery then make sure that the pcm has the proper voltage, ground, etc.. You can add an external voltage regulator and use a gps for a speedometer until you can locate a good pcm.

If it's the Crank Position sensor how do you get to it.? Do you have to remove the radiator? Looks like a bear to get to.

does it register RPM on the tach?

If it does, CPS isn't your problem. You can get to it from the top no problem at all. Pull the belt if it's in the way.

Original poster's info...Last Activity 03-20-2011

Maybe my '93 has a different cps stetup but it was not easy to get to when I changed the water pump the other day.