Pulling my hair out......

B

bigkid

New member
Joined
May 15, 2009
Messages
26
Hello all,
I've been a member for awhile now but this is my first post. This is an excellent site for info. I've searched all over and still can't get my problem solved.So here it goes, I have 2 trucks, a '97 2wd and a '98 4wd 12v. I bought the 98 and the tach was going crazy, no a/c, overdrive or charging. So I searched alll the info on here and came up with CPS. So instead of buying one, first I swaped them and what do you know the 97 is now messing up and the 98 seems fine. So go buy a new sensor put it on the 97 leave the 98 alone, but my 98 isdoing it again. After searching and searching I've readjusted checked for bad wires and have come up with nothing. So I'm lost, does anyone have any other suggestions, could the alternator be bad.
Sorry for such a long first post but any help would be great.
Thanks again
Chris
 
The only other thing that I've heard of with weird CPS issues is a PCM issue. Normally replacing the PCM will fix it. If you want to test, I'd try the 97 CPS in the 98 and see if that helps or not. If not, then replace the PCM?
 
If the CPS is not bad on the 98, it could very well be the alternator. Thats an easy test take it to an autoparts store and they can test it for free. If the alternator is good on most vehicles the voltage regulator is the normal thing to look for. But Dodge decided to put the voltage regulator in the PCM, and they are kinda costly. There is a way to wire an external voltage regulator on them search it on here.

I went through this process shortly after I got my truck and it ended up being the CPS. So good luck.
 
Im kind of new to cummins, but doesnt the crack sensor also have some thing to do with what hes describing?
 
It sounds like it has something to do with the CPS (^^Crank Position Sensor^^) to me. its unlikely that it is something internal in the PCM because usually those kinds of problems will not be intermittent. The CPS is a VRS (variable Reluctance Sensor) meaning that it is a permanent magnet and produces its own voltage as the reluctor wheel ( This being the harmonic balancer) passes through the magnetic field (this is why the adjustment is critical) of the sensor. The PCM reads the fluctuations in the magnetic field and figures out how fast the crankshaft is rotating. Maybe it is just a coincidence that the 97s sensor went bad after switching them? Also it is bad to let the sensors hit anything with the magnetic end when they are removed as the magnet can break and then the sensor is no good...
 
Thank you all for all the input. I'm going to dive back into this thing this weekend and hopefully get it nailed down. I thought about for some odd reason could that sensor have gone bad, so I'm going to check that first I think. But if it does turn out to be abad pcm does it have to be from another 98 12v to work or could I get one from different year of truck?
Thanks again
 
pull your air filter out, take the black plastic cover off your ecm, leave your batteries hooked up, and unplug all 3 modules 1 @ a time then let it sit for about 5 minutes, then plug them all back in 1 @ a time, fire your truck up and see what happens


this fixed my truck
 
Kronic_187 said:
pull your air filter out, take the black plastic cover off your ecm, leave your batteries hooked up, and unplug all 3 modules 1 @ a time then let it sit for about 5 minutes, then plug them all back in 1 @ a time, fire your truck up and see what happens


this fixed my truck
Click to expand...

Why leave the batts hooked up?
 
You must log in or register to reply here.
Top