97CTD4X4-3500

I have a 1997 CTD 4X4 3500, and recently the Tachometer started intermintently jumping all over the place, when the tach starts jumping, usually the warning lights for "Check Engine", "Gen" flicker simultaneously as well as the green cruise control indicator on the steering wheel, when I say flicker I mean like 20 times per second or something(really fast) in bursts. When this happens the transmission starts getting confused, when its at its worst, the truck is barely driveable, and I could probably get around faster on a bicycle. Other times its less frequent. 2000 rpm while driving(pulling) usually seems to easily trigger the issue(its hard to reproduce the issue while parked)

I am posting this after spending probably all day reading up on this issue, and yes, many people have had this EXACT issue.
I have tried some basic things based on my research, I will list them below:

- Went over the grounds/battery connections etc. seem solid. Only problem I found was a worn ground strap from cab to bed - replaced it.
- Re-adjusted CPS gap to a business card, was almost celebrating after a ten minute problem free drive, then it happened again, gotta love troubleshooting intermittent electrical problems!!
- Peeled back the main bundle of wires where the CPS wires meet it, went back about 4", wiring seems fine, no notable issues. CPS wiring connector appears fine, no visable bending/cracking issues.

I currently have two more things I am going to check next:

- I have a new CPS on order, although I will admit in reading previous posts, it definately didnt always solve the problem. For $150 I am willing to rule it out and carry on
- Although I dont know which wire it is(I will try to find out) I have read that the 5v supply to the CPS goes along the back of the block almost into the bell housing, and is subject to shorting out along the way(2 others found the issue here), I will pull truck into the shop and inspect that area.

Other than that, I would love more good and specific suggestions. I look forward to moving on to trying to fix the next issue(overdrive woes)...

Thanks in advance, and I promise to update. This is my worktruck and this issue is extemely frustrating.

Tate

I think you're on the right track. After you said you readjusted the gap, a faulty speed sensor was my next suspect. It would be easier to find a friend with another 12v and rob their sensor to rule out your current one.

patdaly

Just for grins, you say you have inspected the CPS connector, did that include taking the 2 apart and looking at the pins? If not, take it apart, hit the pins with contact cleaner, blow it out and see if that doesn't do it. Where it is located, oil likes to get in there, can look perfectly fine and the oil that seeped in is doing nutty things to the signal.

97CTD4X4-3500

Thanks for the suggestions guys, I really appreciate having good help. Here is my current update:

- As suggested, I have taken the CPS connector, sprayed contact cleaner, and blew it out twice, I have also done that with a number of other connectors, including the fusebox(under the hood) battery connectors.
- I also had my wife sit in the truck and watch the tach while I moved around some wires/connectors. I found I was able to reproduce the issue parked when I fiddled with that wiring bunch that goes down near the bell housing. I mentioned that earlier based on other threads I read. I will continue honing in on this possible short/crossed wire.
- I like the suggestion about trying someone elses CPS instead of wasting $150 on a new one, but I dont know anyone else in the area with my truck. The trucks are almost impossible to find at the wreckers too(probably a good sign) Like I said I'm probably throwing 150 away on the CPS but I need to eliminate it as the problem. I will have the CPS by the end of the day and install it right away and update.

In the meantime I will keep hunting this possible short...
All my work is on hold because of this and finding this problem is my new fulltime job for the time being Not a very profitable venture.

I would love more suggestions or your hearing about your experience with the issue...

97CTD4X4-3500

Strange update:

I have removed the wiring cover/electrical tape from the group of wires that junctions near the back of the valve cover. It goes right up to the cowl area, and down to the bell housing area, and runs sort of along the valve cover to the front. I found that with having my wife watch the tach, when I fiddled with that group of wires, I could trigger the tach to jump all over. Funny thing is, I carefully removed that electrical tape, took apart the wire tubing(whatever you call that wire cover with a rip on one side) and although I couldnt find a short or exposed wire(mind you there are LOTS of different wire) I have went for two 15 min drives, and it didnt happen once with all that wire hanging loose!! I wil put it back together and see if it happens again. Although I now have the new CPS, I will keep it and use it only if the problem persists...

I sure hope this is over...

hauss

here's something else to check, i had the same trouble with a 96, really got my *** kicked trying to find a solution for this one weekend, check the two wire connector on the driver side of the transmission to see if its loose or broken or wet inside, and also check the insulation of these two wires for wearing by the transfer case output shaft, i've seen this as well but likely the problems is with the connection in some way, good luck

ataboy9026

my 97 is doing the exact same things.... sometimes its just the tach needle bouncing up/down a few hundred rpm's and other times as the tach needle bounces the check engine light will flash along with the wait to start light and the cruise indicator light on the steering wheel flashes with the check engine... I also notice a very slight bounce on my speedo needle of 1-2 mph up/down on occasion. I have changed the transmission speed sensor a few months ago and that cured my cruise issues then. I have set ESS gap to .050" and now down to business card thickness with no change. I did notice my speedo reading from 20-55ish mph while sitting still for about 2 minutes about a week ago, but that has not happened since. It acted up every 3-4 minutes for about 1000 mile trip and I pulled AC relay and unplugged AC compressor and it drove without any issues for the next 600 miles then it blinked once. I turned cruise back on and it worked for 800 more miles, Then about 300 miles and now its doing it every few seconds. I took a couple videos of my dash as it acted up I'll post on Youtube and post a link. I ordered a new ESS but I don't think that the problem. Did you ever find your problem?

ataboy9026

ataboy9026

patdaly

After watching those 2 videos, I would be checking every ground in the truck.

I can't tell if it is because of the low lighting conditions and the additional light of the lights flashing on, but it sure appears as if your dash lights are also flickering sometimes as it messes up.

I would say for sure it isn't a CPS problem, and more like a general power supply to the dash area problem.

infidel

Someone on another website had the same problem, perhaps it was you?
My feeling is the climate control is in defrost mode and the A/C is clicking off and on but the clutch is bad causing a big current draw or some kind of interference to the ESS or TPS.

ataboy9026

I have checked all grounds... and reset gap on ESS 2 times... once at .050"and then again down to a business card thickness. And I do have a post on cummins forum about it. I am really leading away from a issue at the dash cluster, I don't think any connections there mean anything to the PCM as they only display info... not send info to the PCM. I mean I think I could take the dash cluster out of the truck entirely and it would still drive just fine... I just wouldn't know my speed,etc... I do have a new clockspring I am going to install along with a new ESS just to rule out those items.

ataboy9026

And I do not have TPS due to 5 speed... and the AC clutch is unplugged and AC relay is out. I asked Dodge for price on new AC compressor and clutch and there is a notice to install a new plug at compressor before replacing Compressor or clutch. I just got the new connector (less than $30).. and I cut the original connector off after I found that out... nothing changed.

97CTD4X4-3500

UPDATE ON THE FIX

Hey Im really sorry I havent responded until now... I must not had my account set to notify me when people post on my thread. Thanks to ATABOY 9026 for private messaging me inquiring about the fix.

In my case, among some other generic troubleshooting steps mentioned earlier in the thread, I had replaced the TPS(which changed nothing) and actually acquired a CPS but figured the problem out before I put it in, so I never installed it. The problem for me was a short in a wire bundle junction, which I was able to pinpoint after having my wife rev the engine and watch the tach while I fiddled with wiring everywhere with the engine running(thank goodness for earplugs!) You wont beleive the releif I felt when I found I was finally able to isolate, stop, and reproduce the issue at will.

There is a tight spot between the brake master cylinder and the fuel shutdown solenoid coming off the engine, in which there is a thick wiring bundle junction, and I could tell there was quite a bit of force pulling that wiring junction down into that tight space, and it was causing a short. (see pics) I didnt even redo the wiring or anything, I just lifted it out, and wrapped the affected part in electrical tape and it was solved from not being pinched anymore(the part of the wire in the picture with electrical tape is the part that was super pinched). It started to fall back in from time to time in after a while(scaring me each and every time) so I put spacer in(second picture), just used a chunk of flexible wiring sheilding. I know its a redneck fix and you could do it better another way but it doesnt go anywhere and it does the trick. I still dont know if two wires inside the bundle were shorted OR if a wire inside shorted to one of those two metal parts in the pinch, but the wires are stiff so u cant just easily turn the bundle and check, so it could be either. On a side note, I had a second issue where the GEN light only was flickering and the tach would jump simultaneosly, and shifting was so bad it was undrivable, but that was the point when I lifted the wiring back out again and put that spacer in and never had the issue again.

All the best and let me know if this works for you too!! I'd love feedback from other folks to see if this is more common or if each case is a slightly different short or something. I hope this helps lots of people, I'm sure some people have had nervous breakdowns over this crap, with an automatic this will turn the workhorse into a useless idling machine and money pit of random unsuccessful replacement parts and service(diagnosis). Most shops may not even be helpful because you need patience and time to find this one and not just throw parts at it. I've seen some folks on forums have gone as far as even getting the dealer to replace the computer which put them in the poorhouse all for nothing. I'm self employed and spent several lost days of work researching and looking for this one.

PS thanks so much to ATABOY9026 for putting the two videos on the thread so people can see what this looks like, the second one shows what this looks like really well, and how all the lights that flicker simultaneously with the tach jump. I will have nightmares tonight after watching that... Only thing different from that video with an automatic is that your tranny would be jumping, hunting and hurting while this is happening and you couldnt tow if your life depended on you. Also, I edited in the correct names of the two parts that pinched the wire, thanks to TORQUEFAN for telling me what the heck they were, I have them simply labled as "this" and "this" in the pic. Please leave that comment there because its a great summary of the problem(I'm bad at summarizing)

ALSO if anyone ACTUALLY needs a brand new in box Napa Echlin CPS part #CSS635, PM me I'll sell it for a wicked price

Cheers.

torquefan

Looks like the wiring was pinched between the master cylinder and the fuel shutdown solenoid. Nice find, I haven't seen that one before.