Stranded - KJ died at idle, no restart

casm · **Joined:** Sun Jan 29, 2006 5:05 pm **Posts:** 694

Not sure if this is a crank sensor or something else, but I'm currently stranded 1300 miles from home.

Symptoms: sitting in drive-thru, transmission in drive, foot on brake. KJ just died without warning. Electrics are all functional, but does not crank (no sound from starter at all). Fuel gauge does not move from 'E' position (tank is full); temperature gauge does not move from 'C' although engine was fully-warm. Gauges pass self-test and were working normally prior to this happening. No sound from the in-tank fuel pump.

Other than poor fuel economy (21mpg), nothing seemed out of the ordinary on the drive out here.

Here's the part that scares me: my OBD-II adapter (ELM327) no longer sees the ECU, so cannot pull codes (assuming there are any). It works fine in one of the other vehicles, however.

Where should I look to begin with this? Finances are extremely limited at this time.

Steve777 · **Joined:** Fri Oct 16, 2015 11:31 pm **Posts:** 279

Sounds like a royal PITA, sorry you have to deal with it...

I'd likely start with the basics. Check to see if your batt has close to 12.7v, and double check that the connections are tight to the batt terminals. Possibly a dying alt let your battery voltage drop to a critical (but not yet dead) level? Try starting in Neutral. If N doesn't work, one can jumper the starting relay (forget which it is, but IIRC it is labeled in the relay box in front of the batt), or what I have done is pry the case off the relay put it back in and just push the relay arm down to make contact. If you have enough juice in the batt that should work the starter, and if done with the key on you should fire up.

Might be worth bleeding the fuel filter to see if there is a bunch of air in there.

And given what you're seeing with much of the electrical system not on, might be worth checking fuses first, since even if you can get the starter to turn, without the ECU it can't run.

WWDiesel · **Posted:** Sun Oct 20, 2019 2:14 pm

casm wrote:

Not sure if this is a crank sensor or something else, but I'm currently stranded 1300 miles from home.
Symptoms: sitting in drive-thru, transmission in drive, foot on brake. KJ just died without warning. Electrics are all functional, but does not crank (no sound from starter at all). Fuel gauge does not move from 'E' position (tank is full); temperature gauge does not move from 'C' although engine was fully-warm. Gauges pass self-test and were working normally prior to this happening. No sound from the in-tank fuel pump.
Other than poor fuel economy (21mpg), nothing seemed out of the ordinary on the drive out here.
Here's the part that scares me: my OBD-II adapter (ELM327) no longer sees the ECU, so cannot pull codes (assuming there are any). It works fine in one of the other vehicles, however.
Where should I look to begin with this? Finances are extremely limited at this time.

Not the crank sensor! You have experienced an electrical fault.
Check all the fuses in the Power Distribution Center under the hood.
Check fuses 6, 16, and 26, either one of these blowing could kill power to ECM
Get a volt meter or a good 12v test light and make sure you still have power to everything.
Sounds like to me you lost power on one of the main circuits?
If you blew one of the main fuses, you need to check all the wiring harnesses real close under the hood around the engine and make sure something did not short out (go to ground) and blow a fuse.
Based on what you have described, you have lost power to the ECM.

flash7210 · **Posted:** Sun Oct 20, 2019 3:00 pm

Have the battery tested.

I once had my battery die while at the mall. It was the original Optima red top battery.
A battery jump box wouldn’t get it to crank.
Jumper cables didn’t help either.
Once I put a new battery in, it started and ran perfect.

casm · **Joined:** Sun Jan 29, 2006 5:05 pm **Posts:** 694

Thanks, everyone. I'm working on getting it moved into covered parking so that I can start investigating without getting drenched. Will report once back after I've been able to do that.

casm · **Joined:** Sun Jan 29, 2006 5:05 pm **Posts:** 694

Well, crap. As far as I can tell, it looks as though the ECU took a dump.

All fuses check out in both panels.

Battery's cranking and holding charge fine.

Can't find any obvious wiring shorts or bad grounds.

No signal from OBD; no CEL during self-test before starting the engine.

Ugh. Need to get one ASAP; can't afford to sit here any longer than is absolutely necessary. Confirmed that the ECU is p/n 56044562CB, so should be good up to the CF revision. Making some calls tomorrow; if anyone has one they can part with please let me know. Really don't want to have to take one to the dealer to have it VIN-matched, but it's my only option around here.

WWDiesel · **Posted:** Sun Oct 20, 2019 10:16 pm

casm wrote:

Well, crap. As far as I can tell, it looks as though the ECU took a dump.
All fuses check out in both panels.
Battery's cranking and holding charge fine.
Can't find any obvious wiring shorts or bad grounds.
No signal from OBD; no CEL during self-test before starting the engine.
Ugh. Need to get one ASAP; can't afford to sit here any longer than is absolutely necessary. Confirmed that the ECU is p/n 56044562CB, so should be good up to the CF revision. Making some calls tomorrow; if anyone has one they can part with please let me know. Really don't want to have to take one to the dealer to have it VIN-matched, but it's my only option around here.

Never heard of one just taking a crap all of a sudden while the engine is running. Most who have reported loosing one has been due to some outside influence like a wiring short.
Guess anything is possible, but highly unusual! :shock:

geordi · **Posted:** Mon Oct 21, 2019 12:22 am

OK - There is virtually ZERO chance that the ECU just died on you.

Things to do: Look at the fuses again, check fuse 16 in the inside box, it is for the ECU and for the AC compressor. If that is good, try swapping the ASD relay in the engine box with another - the fans are a popular option. The ASD cuts power to the ECU and it receives power from the engine fuse #6 according to the wiring diagram.

If still nothing, now you get creative. It MAY be one of the ground points, so do this: On the AC compressor below the engine fuse box - pull the cable to it and look at the colors. The black wire SHOULD be the ground if it matches what the book says. The other should be yellow. Make a jumper (with like a vampire clip) and run the ground wire directly to the battery ground. Hopefully that gets you running again.

Billybob · **Posted:** Mon Oct 21, 2019 2:36 am

Ouch! Can you just confirm if the engine does crank? Initially you say "does not crank" then you say "cranks and holds charge".

If it does crank are there any odd lamps on the cluster...especially the RED Led on the left of the cluster for the SKEES anti-theft system? Check that lamp is not burned out by means of the Cluster Test. Check if all lamps are working.

Replacing the ECM means coding in the VIN as well as the SKIM code so not that quick a fix.

If it does not crank jumper pins 30 to 87 inside the Starter relay socket...make sure you are in Park or Neutral.

Does no harm to at the same time jumper pins 30 and 87 together inside the ASD relay socket.

Could be the Front Control Module (FCM) inside the engine bay has its connector all gunged up with water or dirt which screws the various Busses up.

Could be Ignition switch, bad ground somewhere or bad wiring.

casm · **Joined:** Sun Jan 29, 2006 5:05 pm **Posts:** 694

WWDiesel wrote:

Never heard of one just taking a crap all of a sudden while the engine is running. Most who have reported loosing one has been due to some outside influence like a wiring short.
Guess anything is possible, but highly unusual! :shock:

I'll admit that I may have missed something, but I really do feel like I've exhausted nearly everything that I can reasonably handle here.

geordi wrote:

OK - There is virtually ZERO chance that the ECU just died on you.

Things to do: Look at the fuses again, check fuse 16 in the inside box, it is for the ECU and for the AC compressor. If that is good, try swapping the ASD relay in the engine box with another - the fans are a popular option. The ASD cuts power to the ECU and it receives power from the engine fuse #6 according to the wiring diagram.

All fuses (PDU and in-cabin) were checked and appeared OK; also swapped fuses 6, 16, and 26 with other ones of the same rating just to double-check with no change.

ASD relay was swapped with both the high and low fan relays. No change.

Quote:

If still nothing, now you get creative. It MAY be one of the ground points, so do this: On the AC compressor below the engine fuse box - pull the cable to it and look at the colors. The black wire SHOULD be the ground if it matches what the book says. The other should be yellow. Make a jumper (with like a vampire clip) and run the ground wire directly to the battery ground. Hopefully that gets you running again.

Will have to get my hands on wire & clips; will report back after I've been able to do that.

Billybob wrote:

Ouch! Can you just confirm if the engine does crank? Initially you say "does not crank" then you say "cranks and holds charge".

Apologies - engine in the KJ does not crank on the key. Using that battery in another vehicle, it cranks and starts. Did not explain that well.

Quote:

If it does crank are there any odd lamps on the cluster...especially the RED Led on the left of the cluster for the SKEES anti-theft system? Check that lamp is not burned out by means of the Cluster Test. Check if all lamps are working.

Yep, the anti-theft lamp to the right of the fuel gauge is working. I get just about everything I normally would during a self-test except for the MIL, which never illuminates.

Quote:

Replacing the ECM means coding in the VIN as well as the SKIM code so not that quick a fix.

Yep. Not looking forward to that as a possibility.

Quote:

If it does not crank jumper pins 30 to 87 inside the Starter relay socket...make sure you are in Park or Neutral.

Will do. Have to pick up wire & connectors, so will report back on that later.

Quote:

Does no harm to at the same time jumper pins 30 and 87 together inside the ASD relay socket.

Good point. Will also check.

Quote:

Could be the Front Control Module (FCM) inside the engine bay has its connector all gunged up with water or dirt which crews the various Busses up.

Hadn't thought of that. Will figure out how to get it to in a bit.

Quote:

Could be Ignition switch, bad ground somewhere or bad wiring.

All possibilities as well. I'm also wondering about the likelihood of a bad key, though the RKE is working just fine.

casm · **Joined:** Sun Jan 29, 2006 5:05 pm **Posts:** 694

This is virtually identical to what I'm seeing, except that I don't even get the 3-second start.

https://www.youtube.com/watch?v=-1mFYesTZDo

Mountainman · **Posted:** Mon Oct 21, 2019 1:35 pm

I would look and smell for smoked components at the ecu, and the other module(s) mentioned above. the sudden nature of the failure doesn't sound like a bad ground. The starter circuit also wasn't energized, so avoid testing anything not energized while it's running.
I think the fact that your diagnostic tool can't see the ecu is the smoking gun.
Are you getting 12v to the ecu?

casm · **Joined:** Sun Jan 29, 2006 5:05 pm **Posts:** 694

Tried jumpering the ASD and starter relays. The motor turns over just fine, but does not catch even with the key in the ignition. SKIM light stays on.

Have not been able to jump ground from the A/C power connector yet; will try that later. Did clean the connector for the FCM, which appeared to be nice and clean when I unplugged it.

Have also asked my wife to mail me her Jeep key just in case mine is kaput; I did notice that it has a twist in it. Dealer wanted $325 for a replacement, which is *not* happening.

Apologies if I sound disjointed. The Jeep, Internet access, and the nearest town are all in three different places. Makes for some interesting challenges when it comes to working on it, getting parts, and reporting back.

casm · **Joined:** Sun Jan 29, 2006 5:05 pm **Posts:** 694

Mountainman wrote:

I would look and smell for smoked components at the ecu, and the other module(s) mentioned above. the sudden nature of the failure doesn't sound like a bad ground. The starter circuit also wasn't energized, so avoid testing anything not energized while it's running.

Tending to agree re: bad grounds. My experience with them has usually resulted in gradual problems across multiple circuits sharing the same ground point. Not saying it couldn't affect the ECU differently, but this was a very sudden dropout

Quote:

I think the fact that your diagnostic tool can't see the ecu is the smoking gun.

That's how I'm leaning as well. The OBD-II reader is getting power and attempting to communicate per its LEDs, but it just doesn't see the ECU. I've now run it in two other vehicles and it saw their ECUs just fine, so it's not the reader.

Quote:

Are you getting 12v to the ecu?

That is one of the last things I need to test for. As soon as I can dig up a 12V test light or a meter, I'll be digging into it. Any recommendations on a pinout for the ECU connectors?

Mountainman · **Posted:** Mon Oct 21, 2019 4:00 pm

I think since you have power for the reader that you have power to the ecu, but I'm away from home and can't look it up for a day or two.

foxmiles · **Posted:** Mon Oct 21, 2019 6:41 pm

Oh man! I'm sorry she broke on you! Hopefully it will be something simple. I just got back from a 8hr (each way) trip, but mine did good, EVIC claimed 33mpg, but it's pretty optimistic.

My bt reader will connect to the TCM when the ecm stops responding. I figured that out while I had the ram tcm in, as it read about half the rpm the engine was actually doing. It would get rpm and throttle position as I recall.

You can get pinouts and stuff in the service manual. I don't think it's ok to link it here, but google will fix you right up. Filename is "Jeep 2005 Powertrain Diesel.pdf" and Colorado is the place you want to get it. (might want to get all of the files there sometime, they could disappear for good any time)

The starter relay is grounded(?) through the ECM, and as far as I can see...

Power will be:
(connector/pin)
C1/1 (ASD-relay)
C1/3 (ASD-relay)
C2/19 (start-run)
C2/22(start)
C2/5 (ASD-relay)

Grounds will be:
C2/2
C2/4
C2/6

Triple check your fuses with a test light, swap fuses(of the same size) and relays around with less important systems. The security light could be a clue. Do the remote unlocks still work? Might be worth popping it open and replacing the battery. I bought a key off amazon for $16 and programmed it (had 2 good ones). My scanner claims it can but I haven't tried, might need the secret code.

If there's anything I can try to compare symptoms I'd be happy to, and if you ended up broke down anywhere around Knoxville, TN I'd be happy to drive out and give you a hand.

EDIT: Re-read the thread more carefully and you've already done a lot of that, disregard anything you've checked.
EDIT2: Well the schematics seem conflicted... I'll add the ones from the power distribution in the 2005 KJ FSM. (the C1 pins)

biggfisch · **Posted:** Mon Oct 21, 2019 7:42 pm

These were exactly the symptoms I experienced this summer, sans dying in a drive thru (see thread: viewtopic.php?f=5&t=90166)

First the bad news... on mine the ECM had gone out. Not saying that's what's going on here, but the no crank condition w/key but cranks (no fire) on jumped relay seems telling. I finally figured out that putting the ECM in the freezer for a bit would result in correct operation, but it would die again once everything came back up to temp. When I sent it off for repair, the company told me the processor was overheating and shorting out, and that it cannot be fixed, but they could provide a reman for $1200.

Now the good news... Looks like there's a plethora of used ECM's on car-part.com for around 300 smackers. If you can find one nearby at a salvage yard (full service or U-pull), you might be able to convince the local stealer to reprogram it, or send it to GDE if you have time. I sourced a tuned one from a member, (shout out to my boy TKB4) and gave GDE $100 to reprogram my VIN into it, and the turnaround was about a week from source to to my door. Haven't had an engine issue since (balljoints however....)

If you are near the OKC area, and suspect the FCM/Gateway module, I have a spare I can bring ya, but as demonstrated by the youtube vid, you should still get a 3 second start if its kaput. Hopefully, it's just an issue with the wiring. I'd start with the lower half of the ECM plug harness, as I found this was the half that controlled the communication bus and "let's start the engine" signal. I can't remember if the pinout had a 12V wire on there or not.

Sorry to poopoo on your day. Hope you can get it going again without replacing the ECM.

turblediesel · **Posted:** Mon Oct 21, 2019 8:33 pm

Silly long shot... replace the key battery.

Good luck!

casm · **Joined:** Sun Jan 29, 2006 5:05 pm **Posts:** 694

Mountainman wrote:

I think since you have power for the reader that you have power to the ecu, but I'm away from home and can't look it up for a day or two.

I believe that's the case, at least from what I've been able to dig up. If you can confirm, though, I'd definitely appreciate it.

foxmiles wrote:

Oh man! I'm sorry she broke on you! Hopefully it will be something simple. I just got back from a 8hr (each way) trip, but mine did good, EVIC claimed 33mpg, but it's pretty optimistic.

I hear you. Third time I've done this trip this year; third time something's gone out on me. Ugh.

Quote:

My bt reader will connect to the TCM when the ecm stops responding. I figured that out while I had the ram tcm in, as it read about half the rpm the engine was actually doing. It would get rpm and throttle position as I recall.

Interesting. What's your setup for pulling codes? I'm just using a run-of-the-mill ELM327 adapter and Torque Pro. It's getting zero communication from the ECU; wasn't aware that there was a possibility of it passing through to the TCM.

biggfisch wrote:

These were exactly the symptoms I experienced this summer, sans dying in a drive thru (see thread: viewtopic.php?f=5&t=90166)

Funnily enough, I remember reading that thread a couple of months back and thinking, "ugh, that really sucks, hope he gets it sorted out without too much trouble".

Quote:

First the bad news... on mine the ECM had gone out. Not saying that's what's going on here, but the no crank condition w/key but cranks (no fire) on jumped relay seems telling.

Yep. Correlation isn't necessarily causation, but if it quacks like a duck, it's probably not Toledo, Ohio, either.

Quote:

I finally figured out that putting the ECM in the freezer for a bit would result in correct operation, but it would die again once everything came back up to temp.

Couldn't hurt to give it a shot, but I'm not holding my breath - temperatures got down to 30°F last night, and were around 42°F when I first tried to crank it this morning, so don't believe that it's a heat-related issue. That said, metal contraction, etc. could play a part. Might give it a shot in the morning.

Quote:

Now the good news... Looks like there's a plethora of used ECM's on car-part.com for around 300 smackers. If you can find one nearby at a salvage yard (full service or U-pull), you might be able to convince the local stealer to reprogram it, or send it to GDE if you have time. I sourced a tuned one from a member, (shout out to my boy TKB4) and gave GDE $100 to reprogram my VIN into it, and the turnaround was about a week from source to to my door. Haven't had an engine issue since (balljoints however....)

It's looking increasingly as though this is the route I'll have to take (well, except for the GDE part). The dealer wants $125 for the reprogram; given that right now the KJ is basically driveway decoration and the next-nearest dealer is 25 miles away, they've got me.

Quote:

If you are near the OKC area, and suspect the FCM/Gateway module, I have a spare I can bring ya, but as demonstrated by the youtube vid, you should still get a 3 second start if its kaput. Hopefully, it's just an issue with the wiring. I'd start with the lower half of the ECM plug harness, as I found this was the half that controlled the communication bus and "let's start the engine" signal. I can't remember if the pinout had a 12V wire on there or not.

Thanks - and yep, we are in the OKC Metro. Let's yak further about it when I get back.

turblediesel wrote:

Silly long shot... replace the key battery.

Not silly at all - did that about 6 weeks ago when I was having some RKE problems. It *should* be good, but I can swap it out with another.

Related to that, my wife is getting her key (which is in much better shape than mine) out in the mail to me tomorrow, so I should hopefully be able to rule that out by Thursday or so. It'll also let me bring both keys to the dealer at the same time if the ECU needs to be replaced.

casm · **Joined:** Sun Jan 29, 2006 5:05 pm **Posts:** 694

There was a 56044562CF ECM on eBay, so I bit the bullet and bought it. Mine was a 56044562CB, so at least it'll be a later-revision unit. Worst case, the seller has an open return policy and no-cost restocking. Best case, I get to drive home.

Stranded - KJ died at idle, no restart

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