ajohnson007

OK I have read as much as a can here but Still can't figure this one out. First of all you have a great site and appreaciate any help you can offer.
NO CODES. I get a cannot communicate when I try to check for codes. I only get the oil and airbag lights when I start the truck. No other lights WTS/WIF or a service light. Nothing.
The truck will start But it is not charging. I just replaced both batteries and had the alternator checked twice. I checked what I think is the CPS Sensor wiring (on the front of the block above the crank pulley).
I Also noticed that I cannot get it pased neutral. I was able one time to get it to drive and the truck would die instantly. then I would put it back in neutral and it would start back up. Here is the catch if I goto 1st or 2nd it would run just fine. Is this something to do with the T/C Lockup?
If the CPS was bad wouldn't I still get my lights when I initalally try and start the truck? I Have checked all my fuses about ten times and check all my grounds. Is it a bad PCM? Is there a way to test the PCM. Also what are the pins on the pcm for the CPS? ARE CPS and ESS the same thing?

infidel

Your '97 doesn't have a CPS (crank position sensor) but does have a ESS (engine speed sensor).
If the ESS or it's wiring is bad the PCM will think the engine isn't running and many things won't work. Don't recall it effecting dash lights though.
The way I check PCMs is to trade with one I know works. The PCM is a tough little unit that rarely fails. I've only known of a couple to fail in the ten plus years since they started using them (tex included)

Most times this type of problem is owner caused by installing something new or working around wires and accidentally disconnecting them. Retrace around anything that has been worked on recently. Beware of enlarging any female connectors with a meter probe as it can cause poor contact.
There is a 5 volt output from the pcm that supplies power to the tps, wif, wts and vss (vehicle speed) sensors. If any of them are grounded out it will trip an internal breaker in the pcm, nothing will work.

You can safely continue using your truck, just won't have TC lockup, things might go slow. Engine will run fine even without the PCM.

ajohnson007

Recently the light switch shorted out and was replaced also an aftermarket alarm was removed that previous owner installed. I went through all connections from the alarm and spliced back to origional.

What do you think about the tranny not going into drive? Can the pcm cause this?

ajohnson007

Well I think I am getting somewhere. I removed the the #8 fuse in the PDC labeled fuel pump. All My lights come back on. My batteries are about dead and did not try to start the truck. From what I can tell the fuse supplies voltage to the fuel pump relay the transmission relay in the PDC and the PCM. Is This correct? . I tried putting back in the fuse and removing the relay's but still the same indications as before. What else does this feed? Possible shorted wire down from the PDC. Also where is the connector for the fuel pump located. Is it the one on top of the tank. If so I also tried disconnecting that as well. but same as before.

infidel

Your truck doesn't have an electric fuel pump, that's a 24 valve and gasser thing.
Another place you might want to check is the smaller wires coming off the driver's side positive battery. These are prone to corroding out, often under the insulation where you can't see it. Some are fusible links which can melt also.

Electrical problems can be a real pain, I feel for you.