2000 WJ Laredo PCI BUS Problems :( - Page 2 - Jeep Garage - Jeep Forum

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  #13  
Old 09-28-2015, 02:05 PM
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Re: 2000 WJ Laredo PCI BUS Problems :(

Ok, let me know what the PCM change will do, maybe it will just solve the problem.

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  #14  
Old 09-29-2015, 11:56 AM
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Re: 2000 WJ Laredo PCI BUS Problems :(

Well, I talked to the guy and they're going to work on it for two days more free of charge to find out the problem since they already threw the alternator/battery cable at my vehicle and I doubt I'll be able to get money back out of that so I guess this is there way of justifying it. I'll look at it as preventative maintenance and move on.

I'm going to go pick up my Jeep in two days. It's obvious their electrical guys are highly incompetent and don't know what is going on with it even thogh I've e-mailed them over countless PCI BUS Diagnostic documents that are plastered all over this board and more on how to fix it.

It's funny though. When I picked up the PCM at the local junkyard I was told to use two independent electrical guys instead who had access to DRB III scan tools instead of the dealership. Should've listened. Anyways, I'm out $500 at this point and will just pick it up in two days from now. I shouldn't have got impatient. I probably would've figured this out on my own by now but it's hard working 45-50 hours a week.
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  #15  
Old 10-01-2015, 02:07 PM
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Re: 2000 WJ Laredo PCI BUS Problems :(

So I just received a call from the Service Writer. They did all the diagnostics off of the information I sent them and they concluded that the Driver's Door Module was electronically locked up. He said the guy went through and programmed each module (assuming he reprogrammed the BCM, possibly PCM too to add 'features'?). Anyways, they've test driven it and let it sit overnight and the modules didn't act up which they normally do after 7 hours of battery being hooked back up.

So they only charged me for only 1 hour of diagnostics and the alternator and battery cable. $505. I think I got off pretty easy but now if someone else with my type of Jeep goes to the same place they'll be able to diagnose it pretty easy for someone else.

If you're in the Tampa area, it's Ferman Jeep of New Port Richey. My service guy was Steve Brawer. Hopefully this helps someone else out. I'm still skeptical that the door module could be 'locked up' persay but we'll see what happens.
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  #16  
Old 10-02-2015, 10:48 AM
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Re: 2000 WJ Laredo PCI BUS Problems :(

Unfortunately it isn't fixed. I thought maybe with the new alternator that I'd see more than 13.8v charging the battery at idle but I suppose that's normal for these Jeeps since it's only a 4.0 v6. Anyways I guess I'm going to order a $65.00 oscilloscope off of e-bay that runs off a laptop. I'll have to do this myself from scratch.

The symptoms are gone when the key is on and the engine isn't running. As soon as I start the engine all the problems are there with 5v-6v on the PCI Bus line. I may mess with the diagnostic junction port later this weekend with a DVM and see if one of the modules is screaming for attention over the others.

I still have a backup BCM and PCM on the side as well. Still getting P1686/P1687 as well once it's fully messing up. It starts off with sentry key light on and P1687. Could be SKIM. I'll keep everyone updated.







UPDATE: I went to Ford and picked up a Motorcraft Tested Tough MAX BXT-65 850CA/1090CCA battery. So far nothing has came back after replacement. It's weird. The other battery tested fine at 12.6v+ and 13.8v+ while charging. Alternator also put out 13.8v+ from the post.

Is it possible the other battery was internally shorted somehow but not showing up as 10v? Maybe the battery post itself was cracked/broken? I even loaded tested it and it was fine. I don't know. I guess we'll see in the morning if the issues come back.

I called the dealership and told them it wasn't fixed and he said bring it back. So if I can't figure this out by Monday we'll see what they find out again.
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  #17  
Old 10-02-2015, 08:18 PM
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Re: 2000 WJ Laredo PCI BUS Problems :(

So the problem is related to the running engine. I would disconnect the alternator cable and see what it does with running engine. If ok, then there must be something wrong related to the alternator or charging system. Was the PCM changed? The voltage regulator sits inside the PCM.
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  #18  
Old 10-05-2015, 11:10 AM
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Re: 2000 WJ Laredo PCI BUS Problems :(

Alright. So I took the cap off of the Diagnostic Junction Port. All the other modules seemed to be doing fine, constant 0.1v on the BCM but we can deal with that later once I hook up my oscilloscope.

I found that on Pin 1 there is a consistent 6-7v from either the PCM/PDM/SKIM. So I'm going to start the vehicle and pull the SKIM connector and then measure it with 3 starts up, maybe 5. Then I'll try the PDM.

This took all of 5 minutes to check. The dealership didn't do jack shit with my vehicle. I'll deal with them once I get this resolved. I'll probably use my oscilloscope a little later. It came in late last night and haven't had time to set it up so I'm using a DVM for now.

I'll be back in a few minutes with results. Pulled the PDM and the SKIM and they went down a little bit but that's probably because that's their operational voltage perhaps. However the voltage was still at 6.6v and 6.2v respectively. I'm guessing because I've got the DJP cap off that the voltage is going down from something being electronically locked.

This is all speculation but with just the PCM on Pin 1 it's still 5.5v. So. This looks like a PCM issue to me and since the dealership will put my used one in and flash it for me.... I could skip the oscilloscope perhaps. Keep in mind this is all tested while running and tested 3-5 times over 5 minutes. I'll keep testing it for another 30 minutes. I'll keep the DJP cap off for now to see if the voltage keeps dropping. Maybe the EVR in the PCM is decreasing itself and putting out lower voltage without the DJP cap on?

I won't know for sure until I oscilloscope it and being at work; I have free time here and there to check stuff but maybe not enough time to use that. Back in a bit.

Actually it really doesn't matter. There's not supposed to be consistent voltage on Pin 1 in the DJP no matter what. Because Pin 1 can be measured through the DLC pin#2 when the cap is put on and it's supposed to be 0.5-2.5v with a DVM. I'm ruling this as the PCM and I'll be dropping this off at the dealership in an hour. As much as I want to use the oscilloscope there's no need at this point. I will be making some videos in the future for the PCI BUS issue because there are hardly any videos out there and there's a lot of our Jeeps out there.

I want to give back to the community. I'll let you know what happens later today. They should have the PCM changed and the PCM flashed by the end of the day.
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  #19  
Old 10-05-2015, 11:43 AM
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Re: 2000 WJ Laredo PCI BUS Problems :(

Im not sure if a faulty component can make the PCM increase the bus voltage and stay at that voltage as long as its not reset (by disconnecting the battery). Did you try that already?
Because when im not wrong, is it the PCM which supplies the bus voltage, kind of the master in the system.
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  #20  
Old 10-05-2015, 03:02 PM
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Re: 2000 WJ Laredo PCI BUS Problems :(

The PCM is connected to the PCI BUS from Pin #30 on PCM Connector #3. However, the power looks like it provided by the Junction Block on Connector 3? I've heard of Junction Blocks sometimes going bad but it provides the Data Link Connector with a Fused Battery Supply. It will be something to look into if this doesn't fix the issue which I don't see why it wouldn't. I didn't notice any moisture in the area of the Junction Block/Body Control Module which is another problem. And both big connectors on Driver's Side were free from moisture/corrosion.

I didn't check after resetting the computer by pulling the battery. I've done it multiple times before and all the electronics would work after that and I've measured it then and it was 0.5-2.5 on Pin #2 in DLC.

I got the vehicle down at Jeep now and they're doing it all for free; the computer flashing I mean. We'll see what happens tomorrow after I pick it up. I'll know in 6-7 hours of sitting if it will do it again.

There could be an issue with the body control module but I figure because I used the DVM and not an Oscilloscope.... 0.1v may be normal operation. I need to get that 5-6v off of Pin #1 first.

I thought maybe Crank/Cam/MAP shorting out may do it but I've not had trouble starting it ever. And it's died on me like once which could be due to constantly resetting the computer or something.

I'll keep you updated. They're going to try and get it flashed today but worst case scenario I'll have it tomorrow morning. And I'll let you know what's going on. Testing the DJP with the DVM is probably the best way to figure out what's causing the issue. And even though the issue may be fixed; I'll test it all with an oscilloscope eventually just to get the experience.

Anyways, once this is fixed I'll make a few youtube videos of procedures to check, how to check C200, locations of grounds etc. Seems this information is very rare to find as I've spent 30-50 hours already reading tons of information from google searched.

I'll be back.
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  #21  
Old 10-07-2015, 10:55 AM
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Re: 2000 WJ Laredo PCI BUS Problems :(

It's fixed. It turned out to be the PCM. It's been about a day now and no sentry key light/no christmas tree instrument cluster/ac works. Looks like my diagnosis was spot on. Whoever put those diagnostic junction ports into the WJ Jeeps are genius. It helped narrow down the problem.



If time permits; I'll start making some youtube videos this weekend. I suck at editing so they may be somewhat long but I'll try to follow a script on the side so I don't talk too much and show how to diagnose everything.



Thanks again Frango100!
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  #22  
Old 10-07-2015, 11:21 AM
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Re: 2000 WJ Laredo PCI BUS Problems :(

Good to hear its fixed. Unfortunately for some, they discontinued the diagnostic junction port somewhere for 2003 and up models.
The fused 12V supply to the data link connector is there to supply power to a scanner when connected, it has nothing to do with supplying power to the PCI bus.
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  #23  
Old 02-04-2016, 07:19 AM
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Re: 2000 WJ Laredo PCI BUS Problems :(

I wanted to thank you the time you have devoted to explaining step by step the possible reasons for this failure to have thousands of Grand Cerokee and whose consequences have crazy many of their owners, many forums have been reading this year and experience is the closest to the potential solution, really thank you JGC2000Laredo and Frango100. Sorry for my English.


Vehicle: 2000 Jeep Grand Cherokee Laredo
Engine: 4.7L Straight V8

The symptoms are very similar if not the same, I made some steps that you. so well they described.

Some features:

1. I came the first time in early 2015, first appeared in the light of the ABS, this failure took off anymore, I suppose module is another problem that I have not checked yet, then while the dash lights came on and fell needles tachometer, stopped working the windows, a / C does not cool but it works the engine, checked rubber boots of the driver's door and if it was broken the black cable, I noticed as the days appeared fails again.

2. I checked the rubber boot also passenger door and I got a broken wire was repaired With the routine process, disconnect battery, etc. and the fault is erased, while I Appeared again, check for 3 times and was a driver's door again and was repaired again.

3. I received for one year all grounding, have available manuals and diagrams, changed sensors, etc.

4. One of the things that attracts the attention is that the failure is in the morning when temperatures are cooler and wetter during the day seem that disconnecting the battery remains high as the other day again in the morning.

5. After disconnecting battery I've been watching the behavior from the test connector under the driver's side # 2 DTC and land wheel.

6. For this test I disconnected modules driver and passenger doors, the internal lights off and leave all night WJ battery connection to reset possible codes.
Test by 6 AM, temperature about 12 C

A. With the engine off and not on the WJ, presented between 0.08 Volt

B. Passing the key and not on the engine, it has between 0.5 and 1.5 volt

C. Passing the key and turn the WJ and not go on any of the dash lights, that is, before submitting the fault occurs between 1.5 and 2.5 volts, it is noteworthy that a lit displayed during this period and off white light board every 20 seconds, this happens before turning the light SKIM.

D. About 2 minutes after ignition the WJ and after 4 on and off white light board SKIM light comes on, right now has between 3.5 and 4 Volt.

E. When you turn on all lues board and drop the temperature, battery, etc .. needles has fixed 7.32 Volt.

I can not buy easily the PCM, ECM, ECU, so I need to have a lot of security where the fault is, I have been reviewing and read hundreds of forums and in almost all give different possible solutions, from a new alternator, new PCM, PDM, Cable doors, ground, battery, etc ... and the only certainty is that the cause can not be all at once.

Even the extraordinary Jeff Bach expert analysis has been able to define exactly whether the failure is of alternator, PCM or other module.

I would like to know if after solving the fault in its WJ been clear whether the dealer did what he told you. or were speculation the company Chrysler on the final solution of this problem that has had head to many owners of WJ. really we would much appreciate your opinion.
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  #24  
Old 02-04-2016, 06:37 PM
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Re: 2000 WJ Laredo PCI BUS Problems :(

He Wifei, does the engine start normally when the fault is present?
If it doesnt, then i would remove the shorting cap from the diagnostic junction port under the steering column (so this is not the DLC, where you insert the scanner connector) and see if it will then start. If it does, then the problem is not with the PCM nor SKIM.
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