royta

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'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


edit -- I did not lose my radio, 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.

royta

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

JKM

Check the wires going to the CPS , as well as the clearance on the CPS. That sounds like exactly what it is.

12vordie

Sounds like CPS.

royta

Disconnecting and reconnecting the connector did not fix the problem. Clearances shouldn't be the problem, as it's worked fine for the past year, which is when I bought the truck.

I ordered a new CPS from Cummins this afternoon. P/N 3923129 is $51.87 before the who I know @ Cummins discount.

royta

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.

royta

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?

infidel

Has the PCM connector been messed with?
I've seen bad connections develop when the connector has been disconnected, causes exactly the problem you're having..
Fix is to take the connector apart and squeeze the female ends a little tighter.

royta

No, I've never disconnected the PCM.

royta

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.

infidel

My experience with electrical problems of this sort is that they are most always human caused.
I spent over a month running down a similar frustrating problem that turned out to be caused by the dealer bending a pin while installing a new brake light switch, it was in a location where you needed a mirror to see it. This caused the cruise control to work intermittently, in subsequent efforts to correct this other PCM functions were being lost one by one, it finally ended up like yours is acting.
After finally finding the bent pin the rest of the problems were finally traced to volt meter probes enlarging female connectors causing bad connections.

What I'm saying is the best course to take is to go over everything that has ever been worked on the truck.
The PCM has slo-blow internal circuit breakers that will trip if any of the supply voltages are grounded or the sensors shorted, this will cause you to lose multiple functions at once.

Another thing that can cause this sort of problem is a bad key switch or wiring to it, unless the PCM is getting steady continuous power it won't work correctly. Rapidly flickering voltage to the PCM that you can't read on a meter is enough to mess it up.

BY the way CPS are only on 24 valves and located by the starter, 12 valves have an ESS (engine speed sensor)

royta

Hey infidel. My problems did start after installing the my ISSPRO EV amplifier boxes under the left side of the dash. I hadn't run the wires up the side of the a-pillar yet. Your idea of going over all of the connections that I have fiddled with sounds like a good one. What I find troubling is that it is so intermittent. Last night, on the way home from the Anaheim Angels game, my truck worked beautifully. No problems whatsoever. Intermittent problems are tough to fix, and when you do, you don't know if it is truly fixed, or if it's just hiding for a while.

I know, my FSM does in fact call it an Engine Speed Sensor. I found that out when I tried looking up the CPS, and found nothing of the sort (for the 5.9 diesel - plenty references to the gas motor) in the index.

thesheriff

I had a similar problem as you saw on my posted thread. I do in fact have a 1998 24v with an engine speed sensor instead of a cps. As you know that year had a cross over so some parts that are evident in 12v motors got carried over to the 24v (of that year). I found this out the hard way. The dealer said they had the part in stock and when I went to get it, it was the wrong one. They had to look up a 1997 to get the right part and it took a week for the part to come in. After I installed the new sensor, I noticed it still doing the same over 2000 rpms. The darn thing would not shift into overdrive when it was acting up. I had done everything to specs. I cleaned the dampner and brougt the sensor closer in gap (.40 instead of .50). To my surprise, the truck is back to normal. Maybe this could help. Good Luck

royta

OK, still having the problem. Sometimes I get severe tach flutter, where if I have my foot halfway into it (not enough to keep the T/C from locking while not in OD) while climbing a hill, the engine speed will go up and down, up and down. I know, some of you will think I should look at a mechanical problem, however, those who have actually experienced the problem I am having, will know it is electrical (ESS, TPS, ?, ?) related. You see, when the problem acts up, the trans will drop out of OD and the T/C will unlock, so the engine speed goes up. If I am climbing a hill and not in OD, the T/C will unlock when the problem acts up. When I'm giving more fuel than normal, the problem is easily felt.

Sometimes, the tach doesn't flutter at all. However, the T/C will lock and unlock, lock and unlock. So, I'm beginning to wonder if it is an ESS (Engine Speed Sensor) problem at all.

Today's troubleshooting: I disconnected the TPS, drove down the road, and found out that without the TPS, the trans will not shift into OD, nor will the T/C lock up. One thing I did notice, is that during the short period of driving with the TPS disconnected, there was no tach flutter whatsoever. I was able to play with the OD on/off switch, and noticed the light would not go out like it would if I were experiencing the problem. So, I reconnected the TPS, locked the trans out of OD, and started down the road. Before I even reached enough speed for the T/C to lock in D (not OD), the light had already gone out, indicating that the ESS or TPS had gotten flaky again.

So, I'm wondering if this problem could be caused by a TPS that is going out. What do you think? I've also read that using a regular steel feeler gauge can mess up the new ESS. Will it ruin the new ESS? I didn't have a .050" brass feeler gauge, but I was able to stack several to reach .050". I joined the individual gauges with an 8-32 screw and nut. Yes, the screw and nut were made of standard steel. Yes, while setting the ESS, the screw and nut did come into very close contact with the ESS once or twice. This can't possible ruin the ESS can it? After all, the crank dampner is made of steel, and when attaching the ESS to the mounts, the ESS will come into contact with the dampner prior to setting it to the proper distance. What do you think?

Dualler

Much that I'd suggest has been said already. I do not see the connection between TPS and some problems you are experriencing other than OD. Get the wiring diagrams and study them to see what circuits related to your problems might share wiring. I have also seen defective ignition switches on Chrysler vehicles resulting in multiple intermittent problems similar to yours. Finally, I would check the ground connection(s) related to circuits experiencing problems.