Ignition Switch Removed - Truck Thinks It's Running

[TSimonson]

Hey TDR Gurus,
Sorry I haven't been active in the forum for a while. I've been busy working on my kids' cars and the tractor, but I got home from work on Monday and my truck wouldn't turn off. I first assumed it was the turbo timer, but unplugging the Edge tuner (stock tune) didn’t do anything (like had worked in the past) and the turbo timer screen wasn’t even showing. I checked for codes, nothing. It was just running along like a beast. After failing miserably for an hour-and-a-half pulling fuses, I phoned a friend who came up with the idea to pull the + cable from the power distribution center, a.k.a. fuse box, and it finally died. Sweet.
Now I assumed I had a bad ignition switch. Ordered a new one and installed Wednesday, no change - Truck starts, runs, and drives like a champ, but won't turn off. Still no codes.
To rule out a bad FCA, and not a bad ignition switch from the factory, I pulled the new one out and hooked up the batteries. To my dismay, injector 1 starts clicking, the lift pump comes on, and the instrument cluster is alive like the key is in the run position. I’m sad, but I’m pretty sure it’s not the FCA, and it leads me to believe it’s an electrical short somewhere, that some wire is telling the ECM the key is in the run position, but there’s no ignition switch, much less a key in the ignition. Interestingly, the radio stays off, and the HVAC fan isn’t powered.
So my question to all the electrical gurus out there is, who are the usual suspects to short the truck into thinking the ignition is in the run position? Alternatively, is my theory complete crap? Is there some other possible explanation, like maybe an ECM re-flash will fix it?
I’ll sure appreciate any input. Thanks.

 

[Topzide]

I'd check the TIPM, since you're not "fully" powered up. These are known for weird issues and problems! Hope you can get it figured out.

 

[TSimonson]

Thanks Topzide,
I think Dodge started with the TIPM in 2006, mine's a 2004.5. I'm going to start with the PDC today - precursor to the TIPM.

 

[TSimonson]

...I guess I should have asked if you meant the integrated power module in general, or the TIPM specifically? I believe the TIPM was introduced in 2006, and I understand has been a big problem. My truck has just an integrated power module (fuse box) within the PDC, and I'm definitely going to start there today. I'm thinking run/start F951...

 

[seafish]

On your late 2004 there is an "IPM" attached directly to the "PDC" (Power Distribution Center otherwise known as a "fuse box" ). It is a small silver box. It is generally regarded as unserviceable, though several people HAVE cloely examined the connections and silicone boards inside and found green corrosion which after cleaning did clear up some functional problems that the truck was experiencing.

 

[Topzide]

@TSimonson, Might want to give these guys a shout; https://circuitboardmedics.com/. They offer rebuild service on your PDC/IPM. Common issues are lighting issues, but they say to give them a call with other issues to see if they've dealt with that before. Also just a good bookmark to have.

 

[TSimonson]

seafish - Thanks and yes, the skinny silver box between (not "within" - meant "with". not enough coffee) the PDC and the side of the engine compartment is my next target. I think I also screwed up the F951, I'm pretty sure that's the circuit in the gasser. I'll have to look it up.
Topzide - Thanks for the link. I will definitely check that out.
Time to go pull this mess apart. Thanks again!

 

[Ozymandias]

Check the connectors at the bottom of the PDC, just lately someone had a problem there. It's actually secured and locked connectors but his just disintegrated from aga, falling apart and lost contact so.
Best access is by taking out the wheel well liner, then it's in the open altogether.

 

[Topzide]

Here is one thread; https://www.turbodieselregister.com/threads/electrical-gremlin.275743/
Link from another thread; https://rvtransporterhelp.com/3rd-gen-dodge-pdm-and-fcm-interesting-finds-2003-2-t700.html

 

[TSimonson]

Hey TDR Friends & Gurus,

I hope everyone had a great Easter weekend. I don’t have resolution on this yet, but I think have it figured out, and I’ve learned some things about this 3rd Gen after 21 years and wanted to post an update that may be helpful in the interim.

#1: 2nd vs. 3rd Gen part names: This probably isn’t news to most, I’m probably the slowest kid in class, but I thought the Integrated Power Module (IPM) was an add-on to the Power Distribution Center (PDC - what we used to call the fuse box) in 2nd Gen and earlier trucks. That isn’t the case. The IPM is the whole shooting match, the PDC and that silver thing on the side, which is actually the Front Control Module (FCM) I had referred to earlier in the post as the IPM. I also learned the code reader I bought a couple years ago to troubleshoot my kids’ Subarus will read the FCM in my tuck. Who knew? No codes from that silver box FCM, but here’s the picture showing it all.

#2: “Hope” as a troubleshooting method. I know this is a terrible way to do things, but I did it anyway. After the truck wouldn’t shut off I assumed it was the ignition switch – 21 years of heat cycling, all the internet “these are sometimes bad out of the box” posts, it’s not that expensive, etc. When that part swap didn’t solve the problem, I grabbed on to the reseat the IPM, which is probably what I should have done 1st – Thanks seafish for reminding me that is a thing. So I pulled the IPM, cleaned all the connectors on both sides and reinstalled. No change in symptoms. Everything was still powered up with no ignition switch. Now I needed an actual troubleshooting approach to the problem.

#3: Back to the basics. Topzide had given me a number of ideas and some links to check out, which clicked me into its time to kick in the old school Gen X. Time to dig in to the factory manual and do some real troubleshooting. Since I’m a cheap-a$$ I have the digital version of the manual, it took me about 13 billion clicks between wiring schematics to figure out what I need to test in the physical world. I’m sure most of you could have figured it out in about 5 minutes and 8 clicks, but like I said earlier, I’m not the sharpest knife in the drawer. Anyway, I built this chart to troubleshoot. Spoiler alert, the multimeter values are already filled in from troubleshooting.

To me, this looks like the CAV 3 – 4 is the short. I was hoping it’s a short between the ignition harness and the IPM, but I’m done with hope. So I referenced the relevant wiring sheet from the factory manual.

Seeing that the CAV3 – 4 short corresponded to the IPM C2 harness, I pulled the C2 harness off, and now I have no shorts. Everyone is behaving. This leads me to believe the short is within the circuit board inside the IPM, either in the PDC or FMC. 20 years ago, I may have made the attempt to fix that. Now, not so much. I’ll just buy a new one, unless someone has a better idea? Maybe I’ve missed something?

Again, thanks for all the help on this.

 

[seafish]

I’ll just buy a new one, unless someone has a better idea?

Good job tracking that down.

Like I said, the IPM/PDC connections are eventually prone to corrosion.

That said, what part do you plan to buy "new" ?

I am fairly sure that there are no PDC or IPMs available new anywhere, though you might be able to get it rebuilt.

 

[Topzide]

@TSimonson, I think the only option that is available to you, is to have it rebuilt.

Glad I was able to pass along info that was able to get you to an answer.

Hopefully, one of the repair links will be able to get you up and going quickly. Great job on the figuring! I'm sure this will help others that are searching for answers to the same or similar issue. That's what drew my to TDR! The knowledge of the members helping us through the difficult repairs, and the collection of bookmarks that "we" have saved over the years of ownership of our trucks. I've got a unschooled background in tracing electronic issues in equipment from doing sound productions back in the day. Many times, an amp wouldn't come on before a show, tear it out of the rack and pull it apart! Carried quite a collection of components and soldering gear to the shows, just in case! That being said, tracing wires or circuit boards, to me is like doing puzzles for others.

 

[TSimonson]

Sorry, I just meant an IPM "new to me." I may haunt the U-Pull-Its this weekend, which comes with its own risk, or I’ll go with Circuit Board Medics like TZ recommended.

I also see I failed to include one critical schematic, showing that START F951 off of the ignition harness CAV3 only goes back to the IPM on C1, which is what ultimately led me to the decision to replace the IPM, not chase down other exterior wiring, so I’ve pasted that below.

I am also going to call CBM tomorrow, since the symptoms they list are all the regular FCM problems with lights and the horn, not on the main PDC board. There is one pin (48) on the FCM for RUN-START, but I’m less interested in that, and want to make sure they’re looking at the whole shooting match, not just the FCM. I’ll let everyone know when I get the “new” IPM installed.

 

[Topzide]

@TSimonson, I'd make the call and see what they have to say. As far as the bone yards, that would be a quarter flip! You might get one that works, but for how long, or you might end up with another issue. At least with CMB, you'll get a warranty, and fingers crossed, last as long as it has now. Just factor in the bone yard price, your time (tarot card reading and such) , is worth. Either way, you were able to track it down and get an answer to the issue. You may have found another issue with that setup. Good luck.

 

[Ozymandias]

Isn't that part VIN matched?

 

[TSimonson]

Thanks Topzide, I was hesitant to even put the part about the bone yard in my earlier post for all the reasons you mention. After a good night's sleep, I curbed my enthusiasm on that option and will exercise that for troubleshooting only. If I can get one pretty cheap and test it against my current rig - assuming it doesn't have an identical short - then I think that's a worthwhile troubleshooting step before sending my IPM off to CMB for $600. If the yard lets me take it with the harness, it'll maybe take 10 minutes to pull it. It's only $3 to get on the yard and they may have some bonus parts for my "burner" Subie I'm driving while my main squeeze is torn apart in the garage.

Ozy - DRSM doesn't say anything about being VIN matched and you can buy refurbished ones from MAKS without a VIN: https://tipmrebuilders.com/ So I'm hoping that's not the case. I guess I'll find out!

 

[TSimonson]

I'm going to call this a win. I didn't find any IPMs at the bone yard last weekend that I could use to troubleshoot so I ordered a rebuilt PDC from MAKS. It came in yesterday. I attached my existing FCM to the side, installed the whole IPM, and it fixed the problem from the original post. The truck will turn off when the key is moved to the "off" position. The only leftover gremlin is the "key-in" switch is always on, but that's a nuisance I can troubleshoot tonight and tomorrow with two ignition switches. I no longer need a ratchet to turn the truck off
Thanks for everyone's help on this. Hope this helps someone else, too. I know I learned a lot, even after a "quick" 18 years on TDR.

 

[TSimonson]

I think this is the last update: Re-replaced the ignition switch and constant key-in is fixed. PDC was the issue.