I was pulling a hill on my way to work this morning. I was in O/D w/ torque converter locked. I was losing speed as I normally do when my truck is loaded with material, so I locked out O/D. I don't recall the exact circumstances, but shortly after, my torque converter went out of lock, and I lost my tachometer, speedometer, the alt gauge showed no charging, my A/C clutch unlocked. I pulled over and pulled the lower panel off from under the steering column. I moved the harnesses around, looking for a loose ground or something to that effect. While playing with the gear selector, everything would come back for a split second, and then disappear. I turned around, and my way home, the truck would intermittently lose the above mentioned items. Sometimes, I would only lose lockup of the torque converter, while still keeping tach & speedo. I did not lose my radio and the buzzer still worked when I opened the door. I shut down the truck and restarted fine. Trans would want to start in Drive, so I was forced to manually shift. Tach would bounce around at times too.

I'm hoping somebody has experienced these same issues and can lend a hand. I apologize for not searching first, but since this is an emergency (personal truck/work truck), I wanted to get the question asked in case somebody can give some answers before I find them on my own.

Thank you.

Roy

 

I disconnected and reconnected both the CPS and the TPS. Hopefully it was just a bad connection. I'll report back later.

 

I hope Infidel is watchin. He is good with the electrical..

something is loosing power to the dash and the PCM.. I would check the connections in the main fuse panel on the fender.. Maybe the wires or a fuse are loose there too??

 

I still have dash power during all of this. Fuel, oil, temp, and volts are still functional.

I'm pretty sure it is the CPS. After disconnecting and reconnecting the CPS, the problem went away. I then disconnected the CPS, and the problem was there. Reconncted the CPS and it went away. Unfortunately, it is only going away intermittently. I ordered a new CPS from Cummins this afternoon.

 

Check the harness too for the CPS.. Some guy have the wires wearing through on the harness up on the block..

 

mine did that when I went and put a new PCM in. someone told me it needed to be programmed or something. might be losing power to your pcm somewhere. I am pretty sure that the source comes from your ignition harness

 

It was acting up again yesterday, so I replaced the CPS this morning before heading to work. It appears that the CPS was in fact the problem, as my drives were a pleasure.

 

It is still acting up. It doesn't start until about 20 minutes into a highway drive, both in the morning and the evening on the 26th. It doesn't drop out completely for a minute or two, like it did on the first day, but the tach will bounce and my cruise control obviously drops out when this happens. I guess it could be anywhere on the wiring somewhere between the CPS and the PCM, correct? Could a noisy TPS cause the problem too?

 

Roy, my guess is the wiring from the CPS. It runs along the head and there are plenty of places it could get chafed or it could just break down from heat.

 

royta

The same thing as happened to me on my 97. I have checked everything, well I must have missed something because it still does not work. I don't understand the acronyms used here. PCM, TCS and such. I have checked all wires (I think) and all plugs, and fuses. I am at a loss. I have found some people who have heard of this issue, but nobody can tell me what is wrong.. I was gonna take it to a dealer, but with 197,000 miles, it would be cheaper to sell it for scrap, but I much rather fix and keep..

 

CPS is the crank position sensor, it's on the front of the engine just above the crank pulley. Check the gap with a brass 0.050 feeler and check the wires carefully as far as you can follow them. The senso is not that expensive, so if the wires look good, throw one at it and see what happens.

 

Sunday morning with engine cold, I pull out of the driveway and the tach and speedo drops to 0 for at least a second. So, it appears engine temp has nothing to do with this problem. It also did the bounce at full operating temp too.

Monday evening, I had somebody watch the tach while I moved all of the wiring looms in the engine compartment around. I went through all of the looms, and then started playing with the one on the driver's side, towards the rear half of the engine. The tach bounced around just for a brief moment. I went through all of the loom sections, even the ones directly into the PCM. I was not able to duplicate the tach bouce, even at the loom where it first bounced at. I'm not sure if it bounced because I played with that particular loom, or if it was just coincidence. I also jiggled, jostled, etc. the 3-wire CPS loom, from before the connector to the main loom it feeds into.

Yesterday, on the way home, I had the cruise control set at 70 (obviously in OD). The T/C would unlock for a second, and then lock back up. I was on flat ground, so it was easy to tell it was out of lock, as the engine speed would jump approximately 200 RPM. It did this several times for about a half a minute, but my tach did not bounce like a faulty CPS would cause. The CPS circuit wouldn't cause this, would it? Of course, on the way to the job, I suffered from the bouncy tach too.

Sunday morning, I took some very small needle nose pliers and crimped the female ends of the CPS connector. I almost went to much, as it was difficult to reattach the two connection ends. This is getting very frustrating, and I really don't know where to start.

 

My 97 is doing about the same thing,no OD,lockup, tach volts is what I have noticed right now. I am going to put a used pcm in it and see if that cures the problem. A friend had a snapon computer hooked to it and it wouldn't talk back to him. If this cures the problem this weekend I'll holler back.

 

If the ESS isn't funtioning correctly it tells the PCM that the engine isn't running. None of your PCM funtions will work correctly.

 

I put in a brand new ESS though. Now I don't think there was anything wrong with the original ESS. Is there anything, dampner related, that could cause the ESS to not function properly, thus sending poor signals to the PCM?