I bought a 96 12 valve for a work truck and it needed some loving. I put a new balancer, batteries, alternator and ac compressor. Now the tach and the ac doesn't work and the trans is not shifting into OD. Before we changed anything the trans was shifting fine and the tach was working properly. Would the crank sensor have anything to do with this? We did gap it to .040 and .050 but nothing changed. Thanks for any help

 

Im still having problems with this thing. I have put 3 crank sensors had the trans built. The truck runs good but still has the same issues. The main time this thing messes up is when its cold(lower than 40) or hot( above 90) Anyone got any ideas?

 

Did it work properly before you did the balancer/batteries/alt/AC?

 

I'm not sure if I'm talking out of my *** or not (wouldn't be the first time) but when I had to replace the front gear housing on mine due to the KDP, I had a question about the sensor that hovers over the harmonic balancer. I was told by Cummins that "It's a dodge thing" and then I was told by Dodge that it's a sensor for the tach. I didn't measure gaps...I just stuck it on and made sure it wasn't hitting. That was about 12 years ago and everything is working fine.

 

It is the tach sensor. It should come with a shim to space it properly, which is removed after tightening it down. In the event that it doesn't, something like a matchbook will work.

 

No it has never been right. I ran good for about a month after the tranny was built but then the weather got hot and it started running like crap. The volt gauge was low so I put a external voltage regulator and another alternator on it also but when the gauges and lights start flickering the volt gauge starts dropping and the lights dim. Its got to be something in the wiring. Its around 50 degrees here today and hasn't given me one single problem today except this morning when I first cranked it up. It was in the 30's and 40's yesterday and it acted up all day.

 

I just realized, it looks like I was saying the tach sensor was the problem, which I wasn't. I was saying that is what that is. Regardless, I would pull apart the wiring harness and look for bad spots, working back from the alternator to the PCM. There is a possibility that the PCM is the problem, but that's very rare. And costly, so let's home it isn't.

 

Well I think we narrowed it down hopefully. We took the plastic off that goes around the steering column, you can tap on the ignition switch and all the lights blink as soon as you tap where the plug goes into the switch. Since we left the plastic cover off the truck has ran fine. It was below freezing and it gave me zero problems on the way to work. My ignition switch should be here today.

 

Damn old Chrysler wiring...

 

I hope that fixes it!
Another good check is to hook up your volt meter to one of the batteries. Check DC volts and AC volts. Bleeding of AC noise into the PCM by bad Voltage regulator or alternator diodes has caused Lockup issues on the 47RE tranny. Not sure if this is your issue but maybe worth a look at this link below for the 2nd gen dodges.

Torque Converter Lock/Unlock Issues - Mopar1973Man's Dodge Cummins Articles