AZJeff Posted December 15, 2019 Share Posted December 15, 2019 As my sig lines shows, my MJ has a dashboard from a 97+ XJ in it. I am trying to track down intermittent cruise control light function on the instrument cluster, and I suspect the issue may be a CCD bus communication issue. The CCD bus runs thru the two blind mate connectors on the back of the instrument cluster, and I know there was some sort of TSB related to these connectors having erratic operation. I think the TSB involved changing these connectors to a more reliable design. how can I determine if my connectors are of the older (flakey) design, or the new improved variant! Link to comment Share on other sites More sharing options...
Warren Mohler Posted December 15, 2019 Share Posted December 15, 2019 8 hours ago, AZJeff said: I know there was some sort of TSB related to these connectors There was TSB about erratic operation and possible false TPS code set, I replaced a lot of these connecters per TSB and could not see any difference between new and old and don't know if it ever fixed anything, my 99 XJ had the same problem as described in TSB including TPS code, I believe this was in 2007 the dealership that I had worked at could not find any info on TSB or part #s related to this. I tightened terminals on original and seemed to help out with erratic gauges but TPS code kept coming back till it was replaced it, tightening connecters helped as gauges would weird out once or twice a week before then once or twice a year after, from then on I would just bang on dash when it would happen and all would be OK for a few more months Link to comment Share on other sites More sharing options...
AZJeff Posted December 15, 2019 Author Share Posted December 15, 2019 Were you a tech at a Jeep dealer back when this issue was going on? If so, I have some questions about the CCD bus, if you know anything about the details of it's operation. Please advise and, if so, we can take this to private message to avoid a topic that is not really pertinent to "regular" MJ's. Link to comment Share on other sites More sharing options...
Warren Mohler Posted December 15, 2019 Share Posted December 15, 2019 AMC, Jeep, Eagle 83 to 92, Chrysler Plymouth 92 to 99, back to Jeep till 02. Had lots of bus issues with CP not so much with Jeep. The connecters for this TSB looked EXACTLY the same as what you were replacing, I believe this TSB was just a half assed attempt to repair something they were not sure about as it was intermittent problem, I suspect this is the reason the parts manager and I could not find anything about it in later years, she remembered the TSB as we did quite a few she was service manager at the time so she kept up on info coming into the shop Link to comment Share on other sites More sharing options...
AZJeff Posted December 16, 2019 Author Share Posted December 16, 2019 2 hours ago, Warren Mohler said: AMC, Jeep, Eagle 83 to 92, Chrysler Plymouth 92 to 99, back to Jeep till 02. Had lots of bus issues with CP not so much with Jeep. The connecters for this TSB looked EXACTLY the same as what you were replacing, I believe this TSB was just a half assed attempt to repair something they were not sure about as it was intermittent problem, I suspect this is the reason the parts manager and I could not find anything about it in later years, she remembered the TSB as we did quite a few she was service manager at the time so she kept up on info coming into the shop OK, so here is my problem: I press the cruise control power "on" switch on the steering wheel, and about 1/3 of the time, the light saying "cruise" illuminates in the cluster, indicating the cruise is ready to accept commands. In anywhere between 2 and 10 seconds thereafter, the "cruise" light shuts off, and cannot be turned on again until the vehicle is shut off and restarted. The issue "may" be connected to bumps and jars in the road surface, since I am always moving when I attempt to turn the cruise control on. So far, I have, with the aid of the factory shop manual for a 2000XJ, checked continuity for all wires between the steering column and the PCM, and from the PCM to the cruise control servo. I even temporarily bypassed ALL the wires between the PCM and servo, and between the PCM and the steering column switches. None of that did anything. I also replaced the cruise control servo with new OEM since the connector on it looked "nasty" but there was not change. I installed a different set of cruise control buttons (used) in the steering wheel, but they ohm out with the same impedances as the original set, and thus there was no change there. I even sent the PCM out to the shop that had previously "remanfactured" the PCM before I owned the vehicle, and asked them to confirm if the PCM cruise control functions are normal. They reported no trouble found. I also ran the instrument cluster through it's self-diagnostic tests, and it passes them all per the shop manual. I am convinced the issue is some sort of intermittent connection in the cruise control circuit(s), and I have tested all circuits except ONE. The ONLY part of the system I cannot test is the twisted pair CCD wiring between the instrument cluster and the PCM. Apparently there is a diagnostic tool dealers used to verify the function of this communication bus, but I, of course, do not have that tool. Do you have any suggestions? Link to comment Share on other sites More sharing options...
Warren Mohler Posted December 16, 2019 Share Posted December 16, 2019 clock spring Link to comment Share on other sites More sharing options...
AZJeff Posted December 16, 2019 Author Share Posted December 16, 2019 Oh, I replaced that too, because the horn was not functional. I forgot to mention that. It did nothing for the cruise. Link to comment Share on other sites More sharing options...
Warren Mohler Posted December 16, 2019 Share Posted December 16, 2019 reread your post, sounds like you took CS out of the picture, let me ponder this a little Link to comment Share on other sites More sharing options...
AZJeff Posted December 16, 2019 Author Share Posted December 16, 2019 Yeah, I bypassed the (new) CS, and it had no effect. I ran wires directly from my second (functionally identical) CC switches to the PCM. No effect. This one has me really puzzled. Link to comment Share on other sites More sharing options...
Warren Mohler Posted December 16, 2019 Share Posted December 16, 2019 are we just trying to fix the lamp? does cruise continue to work with lamp off? Link to comment Share on other sites More sharing options...
Warren Mohler Posted December 16, 2019 Share Posted December 16, 2019 I assume cruise inopp with lite off, You said nothing about brake switch. on two occasions I ran into broken pcm connecter terminals broken forward of crimp don't know how they got that way and nothing to do with cruise but VERY intermittent drivability problems Link to comment Share on other sites More sharing options...
AZJeff Posted December 16, 2019 Author Share Posted December 16, 2019 The cruise won’t work. The light does not stay on long enough to see if it works when it’s illuminated. i bypassed the brake light switch temporarily to see if that was the issue. No joy. Link to comment Share on other sites More sharing options...
Andy in Pa Posted December 17, 2019 Share Posted December 17, 2019 I don't know if XJ's have this ability,, but I had to replace the brake light switch on my wifes Yukon. The NC set of contacts were used for the cruise control, and they had a tarnish on them. Cleaned them up (took the cover off the switch carefully) and it worked, but I replaced it anyway.. It wouldn't even allow the cruise to be turned on prior to cleaning the contacts. Is there 3 wires or 2 going to the switch on the XJ? Link to comment Share on other sites More sharing options...
AZJeff Posted December 17, 2019 Author Share Posted December 17, 2019 The XJ brake light switch for the later models has a set of contacts dedicated to the cruise control circuit that are "normally closed" when the brake pedal is NOT depressed. I not only temporarily bypassed this switch (with no effect), but also replaced the switch since it was acting a big flakey for the brake lights anyhow. Still no change. Link to comment Share on other sites More sharing options...
Andy in Pa Posted December 17, 2019 Share Posted December 17, 2019 23 minutes ago, AZJeff said: The XJ brake light switch for the later models has a set of contacts dedicated to the cruise control circuit that are "normally closed" when the brake pedal is NOT depressed. I not only temporarily bypassed this switch (with no effect), but also replaced the switch since it was acting a big flakey for the brake lights anyhow. Still no change. Did you bypass the wire too? If not, it makes me think that maybe its this wire (coming form the NC contact) that may be compromised somehow. Link to comment Share on other sites More sharing options...
derf Posted December 17, 2019 Share Posted December 17, 2019 A broken wire would keep the cruise from engaging. Link to comment Share on other sites More sharing options...
Warren Mohler Posted December 17, 2019 Share Posted December 17, 2019 On 12/15/2019 at 12:21 AM, AZJeff said: how can I determine if my connectors are of the older (flakey) design, or the new improved variant! the TSB connecters had approx. 6 inch wires, heat shrink, you were to strip twist and solder. its a poor setup due to connecters are attached to dash and cluster just pushes onto them rather than snapping into cluster, If it is possible find a DRB3, you can configure to cruise and monitor inputs to see what's going south, might cost a couple bucks but save a lot of wire tracing Link to comment Share on other sites More sharing options...
AZJeff Posted December 18, 2019 Author Share Posted December 18, 2019 10 minutes ago, Warren Mohler said: the TSB connecters had approx. 6 inch wires, heat shrink, you were to strip twist and solder. its a poor setup due to connecters are attached to dash and cluster just pushes onto them rather than snapping into cluster, If it is possible find a DRB3, you can configure to cruise and monitor inputs to see what's going south, might cost a couple bucks but save a lot of wire tracing 11 minutes ago, Warren Mohler said: the TSB connecters had approx. 6 inch wires, heat shrink, you were to strip twist and solder. its a poor setup due to connecters are attached to dash and cluster just pushes onto them rather than snapping into cluster, If it is possible find a DRB3, you can configure to cruise and monitor inputs to see what's going south, might cost a couple bucks but save a lot of wire tracing I assume the DRB3 is a dealer diagnostic tool. What do you think the odds are of a Jeep dealer having this tool as it applies to anXJ? Where does this tool tap into the instrument cluster and the cruise functions? Is it put in line in the cluster-to-dash interface? I ask because my thought is to strip all the trim off the dash, thus exposing the cluster directly, and then go to one of the large Jeep dealers here in the PHX area, and convince the shop to pay them just to run diagnostics using theDRB3. (Showing up with a 1989 Comanche and telling them to run diagnostics on the dash like it was a 2000XJ would be amusing.) I always prided myself on being able to fix all of my XJ’s I have owned, but I admit I am between a rock and hard place here. On the other hand, I am cheap and poor, so I don’t want to write a blank check to a dealer so a young tech. can learn about the primitive electronics of a 20 year old Jeep🤨 Link to comment Share on other sites More sharing options...
AZJeff Posted December 18, 2019 Author Share Posted December 18, 2019 22 minutes ago, Warren Mohler said: the TSB connecters had approx. 6 inch wires, heat shrink, you were to strip twist and solder. its a poor setup due to connecters are attached to dash and cluster just pushes onto them rather than snapping into cluster, If it is possible find a DRB3, you can configure to cruise and monitor inputs to see what's going south, might cost a couple bucks but save a lot of wire tracing I don’t have the upgrade, based on my dash wiring harness. So this improvement was never introduced during production, and all connector upgrades/fixes were dealer installed? Link to comment Share on other sites More sharing options...
AZJeff Posted December 18, 2019 Author Share Posted December 18, 2019 6 hours ago, Andy in Pa said: Did you bypass the wire too? If not, it makes me think that maybe its this wire (coming form the NC contact) that may be compromised somehow. I cannot remember if I bypassed this particular wire (I did SO MANY), but I DID ohm-out EVERY wire in the system (except the CCD bus), with no sign of issues.🙁 Link to comment Share on other sites More sharing options...
AZJeff Posted December 18, 2019 Author Share Posted December 18, 2019 4 hours ago, derf said: A broken wire would keep the cruise from engaging. Yeah, I realize that, and that’s why these intermittent issues are bugging me, since I checked continuity of ALL. Circuits except the CCD bus. Link to comment Share on other sites More sharing options...
Warren Mohler Posted December 18, 2019 Share Posted December 18, 2019 I did a lot of these plugs on XJ and wrangler, don 't recall any bus wires, like I said not many bus problems with the Jeeps at that time, on CP vehicles they were two wires white and purple twisted together, have you seen this in your harness? Link to comment Share on other sites More sharing options...
Ωhm Posted December 18, 2019 Share Posted December 18, 2019 38 minutes ago, AZJeff said: Yeah, I realize that, and that’s why these intermittent issues are bugging me, since I checked continuity of ALL. Circuits except the CCD bus. Continuity testing will only find OPEN circuits. Each wire also needs testing for Shorts to Ground (STG) and Shorts to Voltage (STV). KEY OFF, select Ohms for STG. KEY ON, select Volts for STV. Doing these tests on the CCD bus, if its twisted paired wires will prove out the wiring, not the communications though. Also WIGGLE all wires when testing. Link to comment Share on other sites More sharing options...
Ωhm Posted December 18, 2019 Share Posted December 18, 2019 Twisted paired wires used for communication, cannot touch one another either. Check for wire to wire continuity. Sorry for the can of worms. Link to comment Share on other sites More sharing options...
Warren Mohler Posted December 18, 2019 Share Posted December 18, 2019 they should never run parallel to add on circuits and only cross others at 90 degrees also they were very light wires not much more than telephone wires Link to comment Share on other sites More sharing options...
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