Ive come across a common problem that it looks like many of you have run into before. NO charging, no a/c, no overdrive. its all intermitant. i checked to see if the sensor was loose and it was not so i pulled out the crank sensor to check the wiring. didnt see any nicks in the wires. my best guess now is that the sensor is bad. ive seen that you can use external regulation for the alternator and run a ground switch to the trans for overdrive. is there any mod that can be done to trick the computer that the crank sensor is working properly with out it installed. maybe something i can put on a switch. the computer works so i want to continue to use it instead of bypassing it.

 

There's also a relay on the driver's fender, should be a row of 3 relays. Can't remember the technical term for it but one of them controls voltage output from the ECM. Should be the front relay that controls charging. You can swap it with the rear one, I believe, which is the a/c compressor relay. My 92 stopped charging and that relay was the problem. $6 at NAPA.

 

The computer was intermittant, when charging cut out the od kicked out too. I'm looking for a way to trick the computer to think the truck is running without using the crank sensor

 

You and PatrickBoyle should compare notes, ... majority opinion seems to be the clearance between the sensor and the exciter, 0.050" according to wanna. I fail to grasp the perverse design logic that would make A/C and alt charge to rely on crank speed in the first place.

 

Check the gap with a brass feeler gauge. Mine was off, but correcting it did nothing in my case. Wannadiesel's advice is to take it down to .040". Sometimes that solves the problem. I'm calling mine a bad sensor; going to replace it when I do my KDP in a week or two.

As far as fooling the ECM, you may be out of luck with this sensor. The computer looks for a certain frequency that would probably be more convoluted and expensive to reproduce than just replacing the sensor.

 

I've already taken the sensor out and ordered the new one. Should be a couple days and the beast will be back on the road. Till then its nice weather here in illinois so its harley cruising for me. Thanks for your help.

 

Sounds good. Be sure to update us.

 

Don't worry what the dumb PCM thinks....
The relay you're referring to is called the ASD - Auto Shut Down - I guess because it automatically shuts down everything when the PCM doesn't see a crank signal...
It's the first one of 3 in a row on the driver's fender. Check the leads and wire the side from the PCM to someplace that's hot when the key is in 'Run' -
like the hot side of the grid heater relay

The 3 relays I was talking about are NOT the 3 you see at the lower right - those are headlight relays so I get more power to them. You can see the grid relays - they look like towers...Just to the left of center where I've got a couple of taps coming off...
The ASD relay is below my headlight relays and below the circuit breaker with the yellow caps on it. It sits almost on the wheel inner fender.

 

That wouldn't solve the problem with the overdrive I'm pretty sure. I could just use the external regulator to get the same effect, without tearing into that relay.

 

You win unixcowboy, rock auto called me and said the part is on back order. Time to bypass the computer this weekend.

 

The only thing my PCM does right now is cruise and voltage regulator.

Both work well and neither is high on my 'TODO' list...
Cruise may be a chalenge but the regulator - breeze - I've even got the Mopar Blue regulator sitting in my toolbox...

 

Ok so the truck is back on the road! I ran an external voltage reg, and put the overdrive on a switch. My new plan is to phase out the computer completly. The heater grids will be no problem. Does anyone know how to get the a/c to work?