No Bus After Evaporator Core Replacement
06-13-2016, 08:21 AM
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No Bus After Evaporator Core Replacement
Hey all! I really need some help.
First off: 1999 Jeep Cherokee 4.0 L
Yesterday I replaced my evaporator core and I thought it all went alright. So I reassembled the dash and everything. When I went to start the car, I got a no-bus error on the odometer, and none of my gages work. The airbag light also stays on.
Here are the other circumstances:
After seeing this error, I WAS able to drive around the neighborhood no problems.
I toggled/pushed in/squeezed the connections behind the instrument panel and under the steering wheel to no avail.
I'm pretty sure I got all the connections in when I was putting everything back from the evaporator core replacement.
I checked all the fuses under the hood, and all the possibly relevant ones under the glove box.
Anyone have any tips?????
I can't remember: are there any wire harnesses relevant to the dash behind the heater/evaporator box on the engine bay side?
First off: 1999 Jeep Cherokee 4.0 L
Yesterday I replaced my evaporator core and I thought it all went alright. So I reassembled the dash and everything. When I went to start the car, I got a no-bus error on the odometer, and none of my gages work. The airbag light also stays on.
Here are the other circumstances:
After seeing this error, I WAS able to drive around the neighborhood no problems.
I toggled/pushed in/squeezed the connections behind the instrument panel and under the steering wheel to no avail.
I'm pretty sure I got all the connections in when I was putting everything back from the evaporator core replacement.
I checked all the fuses under the hood, and all the possibly relevant ones under the glove box.
Anyone have any tips?????
I can't remember: are there any wire harnesses relevant to the dash behind the heater/evaporator box on the engine bay side?
06-13-2016, 04:44 PM
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Thank you for the suggestions. I tried both of these and it did not work 
Do you have any other suggestions?
Do you know if the relevant cables, after C201, run behind the heater/evaporator box. If so, do you know if there are any harnesses in that area? Is it possible I unhooked such a harness when I took out the evaporator core box? I don't think so, but I'm clearly not the expert here.
Also, near the steering wheel column, I noticed an unplugged male harness. It's about 1 inch wide, pretty thin, and has six holes (same as the number of gages on the dash, ,yes I realize), it is pointed downwards, and it comes off of the big black mesh of wires just in front of the steering column (you can see it on your picture). I know this sounds promising, but: 1) I think I remember seeing this unplugged before and I had figured it was for optional accessories or something, and 2) I don't see ANY other end to it. Could this be relevant?
I know this is asking a lot, I'm just really trying to figure it out. Thank you in advance for all the help.
Do you have any other suggestions?
Do you know if the relevant cables, after C201, run behind the heater/evaporator box. If so, do you know if there are any harnesses in that area? Is it possible I unhooked such a harness when I took out the evaporator core box? I don't think so, but I'm clearly not the expert here.
Also, near the steering wheel column, I noticed an unplugged male harness. It's about 1 inch wide, pretty thin, and has six holes (same as the number of gages on the dash, ,yes I realize), it is pointed downwards, and it comes off of the big black mesh of wires just in front of the steering column (you can see it on your picture). I know this sounds promising, but: 1) I think I remember seeing this unplugged before and I had figured it was for optional accessories or something, and 2) I don't see ANY other end to it. Could this be relevant?
I know this is asking a lot, I'm just really trying to figure it out. Thank you in advance for all the help.
06-13-2016, 05:06 PM
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'll have to pull my trim panel and knee blocker to see if I can ID that connector. Tomorrow.
That pic I posted is not my Heep. Pinched it off a forum some time ago so I could point out C201.
I like stealing pics. LOL
That pic I posted is not my Heep. Pinched it off a forum some time ago so I could point out C201.
I like stealing pics. LOL
06-13-2016, 05:09 PM
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Year: 1999
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Does your RKE work? There is a white connector on the right side of the HVAC Unit that powers the RKE, which is a module on the CCD Bus.
06-13-2016, 05:15 PM
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I don't understand what you mean. Do you mean the big HVAC box that contains the heater and evaporator core, or the HVAC controls that have the dials like temperature, head/feet controls, and fan speed? Also, how would I know if it is working?
Thank you
Thank you
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06-13-2016, 06:29 PM
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Year: 1999
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The HVAC Unit is the big box with the heater core and evaporator in it.
Another question: Did you disassemble the ground on the extreme right side of the dash and/or the ones on the left side of the dash?
Another question: Did you disassemble the ground on the extreme right side of the dash and/or the ones on the left side of the dash?
06-13-2016, 06:59 PM
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Oh, I do not have RKE.
I did not do much disassembling in either of those areas.
On the right side, during the evaporator core replacement, I undid the antenna, green harness (behind the glovebox) and vacuum tube harness (behind the glovebox).
I don't really know what you mean by "disassemble the ground", though. Is that something I should try? How do you do it?
Regarding the left side, to the left/under the steering wheel, I did not disassemble anything electrical. When I pulled out the dash, we really only pivoted it out, as shown by this guy: https://www.cherokeeforum.com/f2/00-...orator-225178/
(About 1/2 of the way down the page, with pictures containing the orange strap)
I did not do much disassembling in either of those areas.
On the right side, during the evaporator core replacement, I undid the antenna, green harness (behind the glovebox) and vacuum tube harness (behind the glovebox).
I don't really know what you mean by "disassemble the ground", though. Is that something I should try? How do you do it?
Regarding the left side, to the left/under the steering wheel, I did not disassemble anything electrical. When I pulled out the dash, we really only pivoted it out, as shown by this guy: https://www.cherokeeforum.com/f2/00-...orator-225178/
(About 1/2 of the way down the page, with pictures containing the orange strap)
06-13-2016, 08:04 PM
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Some of the bolt/fasteners that hold the dash in place are actually ground connection back to the chassis for the dash components (including the comms bus). So By removing a dash and reinstalling, there is electrical involved.
This video from South Main Auto gives a really good example of the type of goose-chase that can happen. They spent several hours chasing down an electrical problem that also took out the comms bus (obd2). Came down to a bolt/fastener on the right side that also serves as the ground back to chassis for some of the important dash components.
It had been to the dealership more than once, and other shops, and had the PCM replaced about 2 times. In the end...it was a simple bolt that had not gotten tightened down.
Skip to 30:59 if you want to see the moment they realize.
This video from South Main Auto gives a really good example of the type of goose-chase that can happen. They spent several hours chasing down an electrical problem that also took out the comms bus (obd2). Came down to a bolt/fastener on the right side that also serves as the ground back to chassis for some of the important dash components.
It had been to the dealership more than once, and other shops, and had the PCM replaced about 2 times. In the end...it was a simple bolt that had not gotten tightened down.
Skip to 30:59 if you want to see the moment they realize.
06-13-2016, 08:18 PM
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HOOOLLLLYYY CRAP! I think this bolt thing might be it.
So when we were reassembling the dash, the same bolt that they tightened at 30:59 was being tough and I turned it too hard and stripped the fitting. My brother and I then decided we needed to remove that bolt because otherwise it might rattle and prevent the dash from going in. We figured the other ~10 bolts that held the dash up would manage and therefore it wouldn't be a problem.
That said, knowing that bolt and the fasterner/nut that it connects to are gone, how might we go about fixing this? Can I connect a wire to the frame in another way??
So when we were reassembling the dash, the same bolt that they tightened at 30:59 was being tough and I turned it too hard and stripped the fitting. My brother and I then decided we needed to remove that bolt because otherwise it might rattle and prevent the dash from going in. We figured the other ~10 bolts that held the dash up would manage and therefore it wouldn't be a problem.
That said, knowing that bolt and the fasterner/nut that it connects to are gone, how might we go about fixing this? Can I connect a wire to the frame in another way??
06-14-2016, 07:46 AM
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What he was dealing with in the video is ground G107 (the one I asked about in post #8). I'm not sure if this is the "Bolt" you are dealing with.
G107 is the ground for the HVAC and has about 4 other ground wires at this ground point.
G107 is the ground for the HVAC and has about 4 other ground wires at this ground point.
06-14-2016, 07:51 AM
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G108, on the far left side of the dash is also a ground for the HVAC unit as well as for the instrument cluster, A/C Heater Control, and Radio.
06-14-2016, 06:07 PM
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OK so down low there are these two bolts that connect the dash to the main red part of the car (it may be appropriate to call this the frame, I'm not sure). During the evap core work, we took both of these completely out. Only the one on the left (steering wheel) side made it in good when we finished up, because the one on the right broke because I didn't put it in straight
In the video, it really looks to me like he is tightening the bolt down. It's about a 1/2 inch bolt that is maybe 1-2 inches long. I tried connecting the dash to different metal parts of the car, and the negative terminal on the battery, directly using jumper cables. To no avail. I might try that out again, maybe I was just not doing it well. Do you have any other tips?
In the video, it really looks to me like he is tightening the bolt down. It's about a 1/2 inch bolt that is maybe 1-2 inches long. I tried connecting the dash to different metal parts of the car, and the negative terminal on the battery, directly using jumper cables. To no avail. I might try that out again, maybe I was just not doing it well. Do you have any other tips?
