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1998 dodge ram 24v cummins 3/4 ton 4x4 automatic wiring issue.....need help

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I have the above mentioned truck. The ONLY guage that works is the tach. I sent the ECM to cardone to be R&R and they sent it back saying it was fine. I obviously have some sort of wiring issue but weve literaly been tracing wires and making sure theres grounds and 5 volt references and 12 volts....etc for a few months now. Any typical places where a wire might have broken? Any other ideas what might be wrong? Im also looking for a wiring diagram for the wires behind the guage cluster. Those 2 square plugs that the guage cluster plugs into.Any help would be fantastic

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it could just be the cluster is bad. there is a diagnostic for that but i cant remember what it is. have you checke for any DTC's?

  • Author

Ive got a buddy with the same exact truck. I tried his cluster and it did the same thing. I also did the cluster check on mine and the guages worked as they should for the test just not any other time. I would really like to get another harness I just dont want to spend 200.00+ dollars on something that may or may not work.

I had a similar issue a while back. Most of mine were working however. Turned out mine was the ECM. Not sying thats your problem. I think we need a little more help from the more electronicly inclined. i am a novice when it come to that stuff. Did you check for any trouble codes?

  • Author

I pulled the codes but I dont know how many of them are legit to be honest. I sent the box on the firewall (PCM?) to cardone and they said it was fine. The problem is my truck has a PCM and an ECM and unfortunately everyone thinks its the same thing. I got a wireing diagram from the dealership for my cluster but theyre talking about pin 32 and a box having 50 pins but the one on the firewall has 3 seperate plugs with around 30 pins each.......????????

I pulled the codes but I dont know how many of them are legit to be honest. I sent the box on the firewall (PCM?) to cardone and they said it was fine. The problem is my truck has a PCM and an ECM and unfortunately everyone thinks its the same thing. I got a wireing diagram from the dealership for my cluster but theyre talking about pin 32 and a box having 50 pins but the one on the firewall has 3 seperate plugs with around 30 pins each.......????????

First all 2nd gens have a PCM and an ECM. The PCM is on the firewall. It seems a lot of co's. get that confused. The ECM is on the block below the fuel filter canister. It has a 50 pin connector on it. If i am not mistaked the ECM does feed info to the cluster. Please post the codes that you pulled so we can see them. When my ECM went i had codes out the wazoo. They seemed to change sometimes. It was very confusing. If it is the ECM none of the codes are legit. I ran the diagnostic on my cluster and it said it was bad. Now i have a spare cluster. Same thing on the coolant sensor and the apps sensor. I now have spares of both of those. By any chance is one of the codes P 606? That is ECM death code.
  • Author

Ill pull the codes again tomorrow but I did not have a 606 code. Im glad to hear im correct on the ecm/pcm thing I just dont understand why soooo many places have NO CLUE. for all the auto parts stores Ive checked if I say ecm or pcm they refer to the pcm only (on firewall) Including cardone......lol Anyway, I believe my problem lies with the ECM or wires going to it.

--- Update to the previous post...

my codes are 920, 921 and 999 which is no signal from ecm and no pulse signal. I think I got a bad connection somewhere at my ECM (side of the motor)

  • Author

well the other wiring diagrams ive gotten from here have helped and are certainly WAY more helpfull then the diagrams from the dealership.......Thank you

--- Update to the previous post...

Is this the diagram for the 2 plugs behind the cluster that the cluster plugs into? that one seems to be tough from the dealership because it seems like every year is different

  • Author

well Ive got a buddy that has a 1998 just like me and his doesnt match mine either...lol we have 12v, 5v and grounds in different spots thats whats making this so confusing

  • Author

ok ill give him a shot. we shall see I guess......thanks

definitely keep us posted :)

  • Author

anyone know for sure if I used someone elses ECM (on the block) from another 98 24v cummins qc 4x4 truck if it would hurt their ecm?

  • Owner

Shouldn't hurt it but it will most likely not work right because the VIN numbers won't match... Dodge insures that all computers and software are right and proper by using VIN number locking schemes. So if the VIN number doesn't match it might not work... :rolleyes:

I have read through both posts here and at dts and nobody has asked the basic questions.Did you do anything to the rig before this happened replace vp44 ecm or add on any accessories that tapped into the wiring ect?How long have you owned this rig and did the gauges quit while you have had it. Reason I ask Is I did some research on ecm interchangability a few months back and found that the issue you are having can come down to the wrong ecm on the engine. Different year ecms will install and the engine will always run but the primary issue with having a different year ecm is the gauges do not work as well as some other functions like cruise ect.Make sure all pins are pushed into the connectors as well grab every single wire and make sure it is snapped into the connector at both ends. This is a common issue. also it is good to get a replacement male pin to insert into every female recepticle, I deal with this on certain pieces of equipment on a regular basis. the female recepticles can stretch open and will create a non contact issue so by inserting a male pin into every single female socket /recepticle you can feel if it has a snug or loose fit.:thumbup2:

  • Author

When this all started it was very random. I hadnt done anything to it but drive it. Ive had the truck for 1 1/2 years before it starting having this issue. The truck is pretty much stock. The only additions are the stacks and they removed the lift pump and put the pump in the tank. That was all done way before I got it and had never had any problems with it. Until recently we had never done anything to the truck but drive it, change the oil, tranny service...etc typical maintenance. I guess Im wondering how the heck im supposed to test the ECM? if you do a basic search on the net for ecm OR pcm it brings up the PCM everytime. Even Cardone has no clue what theyre talking about. I work at Auto Zone and when I call them and ask them about it they say "oh you mean the box on the firewall, thats the ECM".......NO ITS NOT!!!!!.....lol and they do this for a living!!! Im supposed to trust that theyll send my customers the right parts??....they have screwed us soooo many times and then the customer thinks its our fault.....ugh. Anyway, off my soap box now.....any ideas how to test it? I will check the pins and make sure they are all snapped it. That seems pretty usefull and logical....thank you

  • Author

well I checked the pins as best as I could and didnt find anything but Im going to detach the fuel filter housing so I can get behind it easier.

ALSO, Ive noticed my powersteering keeps freezing up on me at night.....WTH is that all about?? Its cold here but Im sure theres other places that are much colder. Is there some sort of additive or maybe certain fluid I should use.

--- Update to the previous post...

well, they guy you told me to get ahold have said he has no clue about it.....I priced out an ECM and even with my buddys discount its still 1400.00....wth????

--- Update to the previous post...

ok, so my local dealership sucks. I need the REAL wiring diagram for the cluster on my truck.

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Welcome To Mopar1973Man.Com LLC

We are privately owned, with access to a professional Diesel Mechanic, who can provide additional support for Dodge Ram Cummins Diesel vehicles. Many detailed information is FREE and available to read. However, in order to interact directly with our Diesel Mechanic, Michael, by phone, via zoom, or as the web-based option, Subscription Plans are offered that will enable these and other features.  Go to the Subscription Page and Select a desired plan. At any time you wish to cancel the Subscription, click Subscription Page, select the 'Cancel' button, and it will be canceled. For your convenience, all subscriptions are on auto-renewal.