extreme steel

This weekend i notice the batt gauge was low, i put a meter on alternator and just reads 12v i seen a write-up on how to bypass pcm and replace with voltage reg but can find it. also would low voltage stop the a/c from working? it has power coming out of firewall and it seems the low pressure switch is not working. is this something that can be by passed?

81turbota

When my crank position sensor was mis-adjusted, I had no alternator and no ac. I was losing my mind, quick search on the forums showed me that a no alt/ac condition can be caused by:
1. Mis adjusted crank position sensor
2. Bad crank position sensor
3. Bad PCM
4. Bad relays by brake booster
5. Wiring issues related to all of the above

extreme steel

how should the crank position sit? also which relay should i check?

Philip

The gap for the crank position sensor is .050"

No A/C or charging. I would head there first.

extreme steel

Ok thanks a bunch will start there.

81turbota

Try to use a non magnetic feeler gauge as the sensor is magnetic. Just a FYI- I adjusted mine to 0.050" and it still didn't work. I kept playing with it and it kicked in at 0.030". I guess some sensors are more sensitive than others.

There are two black relays on the wheel well by the brake booster, they look like little ignition coils. I don't know which one is which, but one controls the alternator. If you have no AC though, I don't think the relays are to blame.

rrgrassi

What year is your truck?

extreme steel

1992 dodge cummins w-250

81turbota

92 should have the crank sensor. It's at the 12 o clock position above the balancer, secured by two 13mm nuts

extreme steel

got it!! will check it out and get back to you guys. beers on me

Nughuffer

I think the relays you're talking about are the grid heater relays. The other 3 relays on the DS fender are starter, FSS & AC compressor relays.

I agree with others in thinking CPS out of adjustment. Clean the bottom of it if it is covered in oil/dirt before resetting. Also, make sure the CPS isn't positioned over one of the recessed notches in the damper when setting the air gap.

NJTman

You have 3 relays on the inner fender well. Two of them are interchangeable, and you can switch them around to see if it fixes your issue.

https://www.dieseltruckresource.com/...04&postcount=3

If not, then you can look into the CPS. I have an extra one that works, and when I ran into this problem, I simply switched it, and found that it still didn't charge.



Mine issue turned out to be the fusable link under the hood which caused my grief. I temporarily spliced the FL together, and I was back in business, and my Alt charged, the speedo worked again, and I was glad it was as simple as that..... you know, after I switched out the cps and found it didn't change anything..

I now have fuses, and no more fusable links, so I'm not ever having to deal with that mess of crap under the hood again....

https://www.dieseltruckresource.com/...k-t317257.html


BTW, Since you have a 92, the very last page will come in handy for you. The alternator, speed sensor, ECM Fusable link is the white one on the top of the diagram which has two red wires coming from under the fender, and leads to an orange wire on the cab side. Most likely, it's burned inside if you go through the other processes and nothing works.

extreme steel

Well here we go. i checked the crank position sensor and cleaned it and re-adjusted it to 0.40"nothing
tested cps and volts and ohm are fine and checked air gap, checked fuses they are fine. checked relays everything is ok.tested alternator and still no bueno. check the fridge and have about 32 beers left. something. ?????????

thrashingcows

Did you "replace" the Altenator relay on the drivers inner fender? I have had relays the checked out fine...but when put under load they would fail.

patdaly

Is your cruise control working? If so, you can eliminate the CPS.

Sounds like a good reason to find the harness under the dash and wire a tach in.........


I just went thru all this on the Ramcharger, try taking the green wire off the alternator to ground for just a second and see if she goes full charge.

In my case, the PCM was out.......