Rear window defrost not working

[Cmcgettrick]

Hey Guys,
While I had the HVAC panel out I figured I would do a little troubleshooting on my rear window defroster that doesn't work. The switch lights up when I turn the headlights on but does not light up when I push it in to turn it on. I have checked the fuse in location 20 and it is fine. I also checked for continuity on the switch itself thinking it might be bad but it also works as it should. So I wanted to know if there is a relay for the rear defrost, I cant find anything that specifically says there is one. My car is a 1988 M6.
Thanks again for the help.
Chuck

[1986series6]

Looks like the M6 ETM shows fuses 23 & 8, not fuse # 20. Very confusing (pun intended).

Page 0670-1 shows the fuses for 1988 m6. #8-30 amp for defroster and #23 for the light in switch.

https://www.millerperformancecars.co...g%20Manual.pdf

[1986series6]

I found out the same was posted on Big6Coupe later in the day with many
suggestions. Then I suggested what I found the next day.

Hers's what I posted on big6Coupe.

"So, you posted this problem on Bimmerforums July 5th @ 9:03 AM
Then you post on Big6Coupe @ 1:26 PM the same day.

It would be a great help if you mention the duplication on both sites.
So, I didn't see your posts on Big6Coupe, I did searching on your problem
duplicating assistance you received from other members.
Not nice.

I'll post this on Bimmerforums to stop any more duplicating.

Bob V"

[Cmcgettrick]

Bob, I'm not sure what you are trying to stir up here. Here is the post I put on bigcoupe so that everyone has the full story. This seems so childish and I am at a loss for words. If someone wants to PM me (or post it here) to explain what I did wrong please do so because I honestly don't see how posting the same question to 2 forums is a crime. I am brand new to bigcoupe and for the longest time couldnt access some information on that site because I wasnt a paying member. To me this is a perfect example of why you would post to both forums. I'm sorry this has tarnished both these threads.

"Not nice?! What are you talking about?? I am a longtime member of the vintage Corvette community and have always posted on two separate forums when asking for assistance from fellow members. There are plenty of people who frequent one forum over another and often times one will receive different insight from different people. I have never been told that I cant post to multiple forums before and didnt realize that there is some unwritten rule that you cant do so with BMW forums. Last I checked bigcoupe and bimmerforums are independent sites so I'm not sure what I did wrong.
If I truly did something wrong I apologize to everyone that I offended, I did not intend to do anything other than pick the brains of those that have far more experience with these cars than I do. If posting to both forums is considered unethical then I will gladly stick to one forum and considering one is a pay to play its pretty easy to decipher which forum Ill use.

To those that responded, I greatly appreciate the assistance you provided. Thank you."

Chuck

[Cmcgettrick]

Looks like the M6 ETM shows fuses 23 & 8, not fuse # 20. Very confusing (pun intended).

Page 0670-1 shows the fuses for 1988 m6. #8-30 amp for defroster and #23 for the light in switch.

https://www.millerperformancecars.co...g%20Manual.pdf

Thank you for the help Bob. Looks like I might have the wrong owners manual for the car.

[RSheiman]

Perhaps simplistic, but the junction between the wiring and the actual window may be an issue. Can you test the actual female connection in the dash rather than the switch? I believe the wiring (I am stating from my E9 knowledge despite owning an E24 for 25 years) runs along the threshold and then pops up behind the left rear seat. Others can chime in if I am wrong. If you pulled the seats, you may have just pulled out the wiring at the junction.

[1986series6]

OK, maybe I jumped on your case. But, being a long time contributor to help solve problems- I spend about twenty minutes trying to
figure out the ETM circuit on a 1988 M6 that does not have a 20 fuse for the defroster. It's ok that you may have had the wrong info,
so alerting us that it's double posted can give us additional info on what was already discussed.

I stand corrected, I should have PM'd you. I didn't have my morning scotch so I wasn't thinking clearly.

Let's start @ where the info left off and see if we can figure out the solution.

Of course I'll mea culpa on the other site.

Bob V

[Cmcgettrick]

Perhaps simplistic, but the junction between the wiring and the actual window may be an issue. Can you test the actual female connection in the dash rather than the switch? I believe the wiring (I am stating from my E9 knowledge despite owning an E24 for 25 years) runs along the threshold and then pops up behind the left rear seat. Others can chime in if I am wrong. If you pulled the seats, you may have just pulled out the wiring at the junction.

Hey Rob,
Yeah I should be able to check that this weekend. I’m not sure if I can test the female end without powering up the car. I read somewhere that the car shouldn’t be powered up with the airbag removed otherwise an SRS light will come on which requires a special tool to reset. Does this sound correct? My gauge cluster is out being restored.

[Cmcgettrick]

OK, maybe I jumped on your case. But, being a long time contributor to help solve problems- I spend about twenty minutes trying to
figure out the ETM circuit on a 1988 M6 that does not have a 20 fuse for the defroster. It's ok that you may have had the wrong info,
so alerting us that it's double posted can give us additional info on what was already discussed.

I stand corrected, I should have PM'd you. I didn't have my morning scotch so I wasn't thinking clearly.

Let's start @ where the info left off and see if we can figure out the solution.

Of course I'll mea culpa on the other site.

Bob V

All good Bob. Going forward I will be sure to make a note alerting everyone on both forums if asking the same question. Thanks.

[1986series6]

Chuck,

You can do a continuity test on that harness and won't require any ignition power.

Bob V

[Cmcgettrick]

Chuck,

You can do a continuity test on that harness and won't require any ignition power.

Bob V

Ok Ill do that either this evening or tomorrow morning. At this point this might just be the fuse that I dont have in slot #8, I have never had a fuse in there as long as I have owned it. Based on my owners manual I shouldnt have one but I think its clear I don't have the correct owners manual. Im not sure I can test the function of the switch with the fuse in without turning on the car?

[1986series6]

Chuck,

I agree, without that #8 30amp fuse- the circuit would never work. That makes me suspicious, why wasn't there a fuse in that slot. When you're ready with the dash in place to fire up that circuit, be prepared for any unusual surprises.

Bob V

[Cmcgettrick]

Chuck,

I agree, without that #8 30amp fuse- the circuit would never work. That makes me suspicious, why wasn't there a fuse in that slot. When you're ready with the dash in place to fire up that circuit, be prepared for any unusual surprises.

Bob V

Exactly! Had a neighbor (e30 M3 owner) over yesterday and he was looking at it and I said that exact thing to him. We both sort of shook our heads and at the end figured we have to give it a shot when I get the cluster back.