Left auxiliary on all night, now No j1850 msgs is on my EVI

Mountainman · **Posted:** Thu May 07, 2020 12:04 am

Stupid tired, I rolled up the windows on my parked jeep and left the key in the aux position. When I went out the next morning the rear glass latch was rhythmically activating, cha-chunk cha-chunk etc. I was thinking, oh no, i've fried the associated control module. Well, it still runs fine, but I can't get temp on the evic anymore, and my homemade self tune won't do it's high idle thing anymore, which really sucks (wet-stacking).
Anyone know which module this is and if it's going to (God forbid) require a trip to the dealer after I install a new one?
Or will a drbiii suffice?

At least it runs, so I can swap it at the dealer if necessary and avoid towing fees...

Thanks for reading

foxmiles · **Posted:** Fri May 08, 2020 7:14 pm

Probably a dumb question, but have you tried disconnecting the battery for a while to see if the module just resets? Sometimes low voltage glitches stuff and it doesn't reset properly until you remove all power.

Billybob · **Posted:** Sat May 09, 2020 9:54 am

Is this the standard Cluster you are referring to ? Saw a pretty identical post recently on jeep.kj forum.
User left lights on and ended up replacing the battery if I remember correctly.

Likewise for him the temp gauge would still not work.

I advised him to do the Cluster Exercise by holding the Odometer Reset Button IN while turning ignition ON.

He did this...all the gauges moved, lamps lit up etc.

When he started the engine the stuck gauge worked fine! :shock:

Section 8J in the manuals actually tells you to run this procedure if one gauge is not working properly...if any gauge not moving correctly then replace cluster assembly. :cry:

Pretty sure the BCM does the work here but I would need to check the wiring diagrams, the cluster itself is driven by the PCI Bus. :wink:

Mountainman · **Posted:** Sat May 09, 2020 1:04 pm

Oops, I should have said the EVIC temp only, the cluster is all good. I removed power for days while doing ARP retorque.
99% sure it's the FCM, as I thought it was a seperate issue, but the WIF light has been going on and off for months (drained filter, no change), and it's also controlled by the FCM. Too bad both of the jeeps I'm working on at my cabin are 06's, I'll clean contacts and swap FCM next week .
On a side note, I finally see an advantage with the 06's, no FCM!

Billybob · **Posted:** Sun May 10, 2020 2:45 am

Yeah the FCMs on the 2005 CRD have proved to be a major problem....any issue there can hold up all the Busses...PCI, CAN, SCSI etc. which can cause problems everywhere. :roll:

krb · **Posted:** Sat May 16, 2020 6:50 am

Any luck yet?

Mountainman · **Posted:** Sat May 16, 2020 11:25 pm

I had a minute yesterday and went to swap it but the bottom bolts are all corroded, so I will have to go back after it in the next few days

Mountainman · **Posted:** Wed Jun 03, 2020 1:04 am

Ok, swapped the fcm, and nothing change for about a week, and then full function came back for days, and then back and forth again today. When I started it this evening it had coms back, but all of the dash lights are out. I cleaned the typical problem ground behind the headlight, so I don't think that's the problem. Looks like it's one of the other modules that's damaged. Anyone happen to know what controls the dash lights?
Off to the wiring diagrams when I find time...

Billybob · **Posted:** Thu Jun 04, 2020 9:55 am

I am pretty sure the PCI bus controls the cluster lamps as well as the logic built into the Cluster itself!

I will look through the logics...may be a fuse or grounding problem.

Mountainman · **Posted:** Thu Jun 04, 2020 12:06 pm

Billybob wrote:

I am pretty sure the PCI bus controls the cluster lamps as well as the logic built into the Cluster itself!

I will look through the logics...may be a fuse or grounding problem.

Thanks! I'm pretty sure the dash lights went out a year or two back, but they came back. Sure makes night driving interesting!
The coms are back again, but the dash is still out. I'll have to figure out which ground is associated with the modules besides the ecu, which I relocated this time, as it was already looking bad after 2-3 years since I cleaned and connector greased it.

Mountainman · **Posted:** Thu Jun 04, 2020 12:18 pm

What's this pci bus you mentioned? 2005 crd has one?

Mountainman · **Posted:** Thu Jun 04, 2020 12:30 pm

Mountainman wrote:

What's this pci bus you mentioned, ? 2005 crd this in its hybrid bus?

WWDiesel · **Posted:** Thu Jun 04, 2020 3:37 pm

According to the FSM, 8W-40 INSTRUMENT CLUSTER page 2 the ground for the instrument (dash) lights is under the dash on the left (drivers) side. (Drawing 1)
G202 Left Kick Panel (Black Connector)
G202 also supplies a ground to several other things. See 8W-15 GROUND DISTRIBUTION, page 11
You could also test the circuits for the dash lights at the connector plug on the back of the instrument cluster.
The ground wire is the Black/Light Blue wire. See picture below.

Mountainman · **Posted:** Thu Jun 04, 2020 4:21 pm

Many thanks WW! I'll have to see why the bright light indicator light works but the backlighting doesn't. Maybe it's just the nighttime back lighting that's out

WWDiesel · **Posted:** Thu Jun 04, 2020 4:40 pm

Mountainman wrote:

Many thanks WW! I'll have to see why the bright light indicator light works but the backlighting doesn't. Maybe it's just the nighttime back lighting that's out

If you have 12v on the wire feeding the cluster lights, and the ground wire is good,
Do you think all the bulbs are bad?
I have replaced two of mine. They are replaceable. I found the bulbs online a few years ago.

Mountainman · **Posted:** Fri Jun 05, 2020 1:45 am

Nah, it's an all or nothing problem that i've seen at least once before. Like a sticky relay, or perhaps a bad ground. I do everything on my phone these days and wiring diagrams are not exactly very easy to see and navigate on a phone lol
I do have bad bulbs (hopefully) for my gear selection lighting though, and part of my climate control. Hmm, sounding more and more like a bad ground, and maybe thats causing my bus problems too. Working at my cabin for 2 months, need to bring the laptop up here for diagrams...

Billybob · **Posted:** Sun Jun 07, 2020 3:11 am

Mountainman wrote:

What's this pci bus you mentioned? 2005 crd has one?

It sure does...according to the Wiring Diagrams..8W-40-4.

The early KJs like my 2002 Export CRD only uses the PCI bus.....impossible to get a reader to read any codes.

According to the 2005 Jeep KJ Service Manuals the 2005/6 KJs use PCI, CAN and SCSI in different combinations in different places!

Probably why the FCM causes so much trouble as all of these busses get routed through it! :shock:

Mountainman · **Posted:** Sun Jun 07, 2020 6:18 pm

Sheesh, I wish it was easy to switch all 6,000 mods to an 06, but I've replaced almost everything....

Mountainman · **Posted:** Sun Jul 05, 2020 12:28 am

WWDiesel wrote:

According to the FSM, 8W-40 INSTRUMENT CLUSTER page 2 the ground for the instrument (dash) lights is under the dash on the left (drivers) side. (Drawing 1)
G202 Left Kick Panel (Black Connector)
G202 also supplies a ground to several other things. See 8W-15 GROUND DISTRIBUTION, page 11
You could also test the circuits for the dash lights at the connector plug on the back of the instrument cluster.
The ground wire is the Black/Light Blue wire. See picture below.

I finally went after troubleshooting my lack of cluster lights, and bus communication.

After much reading of the manual and diagrams, I:
-pulled the instrument cluster, and found that the connector pin numbers don't match (cluster vs diagram). That made me hesitant to provide the ground that the BCM provides (switched ground). So all I really verified was that the battery 12v (constant), was present. Luckily I have an army of crd's, so I swapped the cluster vs possibly shorting something out. No change...
-I learned that all the dimmable lights, (cluster included) are PWM supplied by the BCM. If that was present the lights would work (2 different clusters) so I landed on swapping the Park Lamp Relay. No change...
-i also check fuse 34 early, and by pulling it and putting it back, I went from having coms to no coms again (it has still been intermittent).
-i also verified that the original rear door latch switch problem IS also controlled by the BCM.
-last 2 things I can think of to check are the dimmer switch, but it successfully dims the EVIC lights, which pretty much verifies that it is good. And then there's the BCM, and I'm not certain that i've verified its ground yet. Any clue where it is?
Does anyone know if I plug in another identical p# bcm, if it will be safe to look for the dash lights to work? Accordingly, do the dash lights come on when the engine isn't running, because the BCM has to be VIN programmed by the dealer right? :banghead:

Thanks for reading

joe_ · **Posted:** Thu Jul 09, 2020 8:47 pm

Mountainman wrote:

Does anyone know if I plug in another identical p# bcm, if it will be safe to look for the dash lights to work? Accordingly, do the dash lights come on when the engine isn't running, because the BCM has to be VIN programmed by the dealer right? :banghead:

I think the VIN verification checks with the PCM, and I think the PCM is only powered when the key is turned to ON (and obviously START as well).

Reason I think this: I grabbed an RB1 nav radio at a junkyard, pulled it from a Dodge. Installed it in the Jeep, turned the key to ACC, and the Dodge logo appeared on the radio display when it first powered up. Cycled the key between OFF and ACC a few more times, and the Dodge logo appeared on the radio each time. Turned the key off, and then turned it to ON. This time the Jeep logo appeared on the radio, and it's had a Jeep logo on startup ever since. Seems like once I turned the key to ON, the radio was able to grab the VIN from the PCM and realized it was now installed in a Jeep.

Left auxiliary on all night, now No j1850 msgs is on my EVI

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