where is the regulator on these? is it on the alt or external?

 

Sounds like crank sensor trouble to me. Does the truck have A/C, cruise, or OD and does any of it work?

 

yeah i was just gonna ask about the crank sensor.
i dont have ac or cruise and i have a 5 spd manual. i dont think i have overdrive. there would be a button or switch or something for that right?

I did however try to hook up a tach to the factory wiring and it did not work, so that brought me to looking at the CPS. but it also could just be that my cheap tach isnt compatible.

i started inspecting the Cps wiring and found some exposed (but intact) wires right at the top of the block where the wires are mounted and drop down behind the rad hose.

ive read on some other threads about testing the sensor clearance. how do you do that? do you remove the sensor? Can i remove the sensor to repair the wiring without screwing anything up? could i use a meter on the wires to find problems? should there be a current? or how would i do that?

Also, if it was my CPS, would i still have 14 volts at the alt output or could a bad CPS or bad CPS wiring reduce voltage at the alt. and batt. to 12.3ish

I also checked the blue wires on the back of the alt. with a meter. unless i did it wrong (black to ground, red to each of the two) i got no reading at all.

 

I would bet you have a cps problem. You do have od mut since your truck is a manual it is not affected by the bad cps. Only an auto truck is affected like that when the cps goes bad or the wiring to it. That is probably why you have no ac and no cruise and it is not charging. The computer regulates the charge voltage. If it was externally regulated there would be a metal voltage regulator bolted to the firewall somewhere. Please go to the usercp and fill out your signature it will make helping you much easier in the future.

 

Well, there's your problem...

Yes, take it off and fix the wiring. When you put it back the gap should be 0.050" or a little tighter. Don't use a steel feeler gauge, if you don't have brass or plastic ones fold a matchbook cover in half or a business card in quarters and you'll be close 'nuff.

 

ok so i removed the sensor. ( man that was annoying!)
The section of bad wire was right against the plug so im bypassing plugs.
hooked it all up, used matchbook for the gap.

fired it up and now im getting even less voltage. 11.4 at the batt and alt.
why would the voltage have gone down? maybe i should have a smaller gap?
then i tried just completely disconnecting the sensor. same voltage, no change when the sensor is unplugged.

 

Maybe the sensor itself is bad. Or maybe the computer could also be bad.

 

The voltage went down because you are draining the battery some every time you start it, it's still not charging. You didn't use the whole matchbook, right? Just the cover folded so it's double-thickness...

Did you check the harness all the way up and around the front of the engine?

 

yup just the cover folded once.

the wire looked fine all the way up until the plug. so i cut off the plug and added a bit of wire. then connected it to the female plug.

should there be any power going to the CPS? if so i could check it on the female plug with a meter right?
how common is it for the actual sensor to go bad?

should there be power going or coming out of the blue/green wires in the back of the alt? cause i got nothing on them.

 

Yeah, we've already established that the field is not getting power. Check out the ASD relay and its connector. The one time my truck stopped charging it was a bad connection there. ASD relay is on the fender, look at the "What are all these wires?" thread in the sticky to see which one I'm talking about.

 

alright ill go take a look right now.

 

alright so the wiring at the ASD looks good i didnt check it all from the relay to the CPS plug but the wiring looks new almost so i think it should be alright.
and i tried switching it with the AC relay. but no change.

are the Blue and green wires in the ASD relay the same ones leading to the back of the alt?
the blue wire is getting 11.3v
green is getting nothing

 

Try looking here; https://www.dieseltruckresource.com/...n&onlynewfaq=1

And here; https://www.dieseltruckresource.com/...18&postcount=4

The first will get your truck operational until you can decide what to do. I'm not sure where it is but I'm pretty sure there's something about running air-conditioner without a computer. But there is no fix for the cruise control without the computer to the best of my knowledge

 

befor i get a new cps (which no parts stores seem to have here)
are there any other things i could test first to narrow it down to the cps?

also all i can find are ones listed for automatics.
do the manuals absolutely need one or is there a way around it?

Would bad battery cables have the ability to lower the voltage output right on the batt. terminal of the Alt.?

 

Yes there is ---
But it screws up your speedo....

You can find a cruise control from a late '70s or early '80s chrysler and then convert to cable speedo drive, then you'll need to also get a cable speedo from an earlier truck - I think the '89s - '91s had cable speedos...
Acutally those cruises kept the speed a lot more constant than the computer controlled ones do.