Monty

Does anyone have a to and from explanation of the wiring for the crankshaft posititon sensor? Pinouts of the connectors etc? I have the schematic but I am not were I can get to it.

Trying to trace down a tach fluctuatin problem. Pretty sure it is in the wiring because I can have someone move the harness at the front of the engine with it running and the tach will start jumping around. Also, the first relay on the drivers side fender well closest to the front of the truck is clicking on and off when I move the wire with the truck running. Again, I am without my manual, so what the heck does it control? Thanks

Monty

Junk Yard Dog

Monty, over in the 12 valve engine and Drivetrain, someone just had similar probs. It's the post by warden. Hopefully you have the same probs.

Rick

Monty

Thanks for the link. However, mine is a 5spd so it doesnt have a TPS. Which is good in this case LOL.

wannadiesel

Well, according to my '93 manual that's the fuel pump relay. I don't know what the guy who labeled the picture was smoking. It's actually the automatic shut down relay, which supplies the field ground to the alternator. The PCM is losing the tach signal intermittently, so it keeps turning the field off every time the engine "dies", and back on when the engine "restarts". CKP pin out is: tan/yellow is 8 volt supply from PCM, gray/black is the pickup signal to the PCM, gray/light blue is the common sensor return/pcm ground.

Monty

Thank ya sir So let me see if I am following you here. The relay is kicking on and off while running and moving the wires because the PCM is loosing the voltage reference (signal) from the tach? But, if it is the auto shutdown relay and it is kicking off and on, you would think that when it kicked off it would shut the truck down but in this case it isnt.

wannadiesel

I don't know why they call it the ASD relay, its only function is to supply ground to the field winding in the alternator when the computer senses through the CKP sensor that the engine is running. It has nothing to do with shutting down anything but the charging system. They oughta call it the field ground relay, but that would make too much sense.

Monty

Ah ha. Thanks, will have to troubleshoot it tommorrow.

wannadiesel

Hey Monty, I got the function of the ASD relay a little bass-ackwards in my memory. The ASD relay supplies B+ to the alternator field and the PCM regulates by pulsing the ground. Doesn't make any difference in your situation but I hate to leave erroneous information uncorrected. Would have been smarter to look at the ASD relay wiring diagram at the same time I was looking up the CKP sensor pin-out.

Monty

Thanks for the clarification Dave

I looked it over today. Removed the CPS and ohmed out the wires from the CPS connector back to the PCM and all showed to be good. I did notice before I started that my voltage gauge was erratic and would clear up when I moved the CPS wires. Put everything back and set the gap of the CPS and tried it out. Got nothing, hooked the multimeter up to the batteries and they were not charging and no reading from the tach. Called Dodge and ordered a CPS. It wouldnt be in until Friday so I hooked up an external voltage regulator to get me by until Friday. Charging good now..15.5 max LOL. However, my lights are flickering a little from feedback with the regulator hooked up which is no biggie.

greatwhite

Monty, the wires aren't worn where they run thru the clip at the front (top?) of the head or broken where they go into or out of the 3 pin connector? If it is intermittant, I would suspect that before PCM. PCMs by the nature of the beast I would think, would be a pass/fail type of thing. Works or doesn't. Working off and on sounds much more like a harness issue to me. Just my .02 Rick

Monty

Good point Rick, thats what I figure has happend. I have traced all wires from the first breakout point of the CPS wires which is at the front of the head (3pin connector) back to the PCM. This leaves only the 2' strand running right into the CPS

Monty

Sensor was the culprit like I figured. Also found out that the PCM will show some resistance on the ground side of the sensor.

wannadiesel

Cool. Glad to hear you got it fixed.