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Sunroof is jacked!!!

8K views 77 replies 10 participants last post by  Chris0nllyn  
#1 ·
So, I've had issues with my sunroof for awhile, sometimes it has power to the switch, sometimes it doesn't... but I pulled the motor out and tested it, it works fine...no issues there.

Fuse isn't blown, but had a LITTLE bit of corrosion on it, so I put in a new one. That is getting
power through the fuse.

So, I thought it was the switch...got a new one...still no power (well, off and on)

I'm thinking it's a bad ground....it's grounded to the roof, above the headliner, right above the windshield...

Using my multimeter, I tried different grounds, and I'm confident I'm not getting power at all....but why other times?

I also cleaned the contacts in the fuse box, opened the fuse box and checked the connector on the bottom...I;m stumped here...Any ideas?
 
#3 ·
sounds like your gonna have to trace wiring from the fuse to the switch....corrosion on the fuse doesn't sound good...Run a continuity check using your multimeter from the switch side of the fuse to the switch itself.......if you have continuity try the wiggle test on the wiring to see if it breaks.....also you might wanna look at the underside of the fuse block for signs of green monster (corrosion)......
 
#5 ·
You're right, it's only one wire coming from the fuse box to the sunroof...I check every connection along its path and there's no corrosion or anything....When I said corrosion I meant VERY little on the fuse prongs...thats all....no where else.

I'm wondering if it's the cab ground....
 
#8 ·
Hold one!
 
#9 ·
#11 ·
The grounding of these trucks and BCM is one fuckin wierd system.

Paul was having issue with everything from his stereo to his gauge cluster bc of that one grounding point under the hood Chris. I'm sure some how the sunroof is running through the BCM. I hope that fixing that one ground fixes the issue(s)
 
#13 ·
Yeah standing in front of the truck its to the left over the inner wheel well, in front of the intake!
 
#15 ·
at least your trucks are better than the bonneville, lesaber, etc. those had common grounds too. near the door jambs on the floor board so nice salty wet snow boots corrode them. come on GM pull your heads out your ass and do it right.

one easy thing to do is a run of wire straight to the battery to test ground. also sounds stupid but is their primer or paint on the grounding point that is usually the culprit right there
 
#18 ·
And I'm sure you were going to do it, but after you clean up those contacts...add some of that dielectric grease shit!
 
#23 ·
Yeah I want to get back to finish up my rear suspension project that I never finished while back!
 
#29 ·
The sunroof circuit is just common power, common ground and a 2 direction motor...thats all...I'm getting no voltage at the switch...but 12v across the fuse...I'm using the same ground as the switch for my meter.

I also tried different areas, and tried scraping the paint away with the test lead for the ground and still got nothing.

I appreciate the help man...I used to be an electronic tech and did all kinds of work on electronics, and now I draft/design electrical work, so I know what you mean.
 
#30 ·
So problem is in the power circuit between the fuse and the switch...you ARE testing on the battery side of the switch?!? I'm not tryin to be a smartass.....everyone has there days....including me...

Also to confirm you could run a test lead between the ground and the Negative terminal of the battery...at least that way you know the ground is ok....
 
#32 ·
lol, yea I have my days also, but yes it's the power side...I can literally see the ground for the switch right in front of the sunroof motor. Plus the wires are red and blck, so thats a plus :lol:

I'm going to try the test lead deal tonight....I'll leave the power wire and ground to the battery and see what I get.

You could run a new power wire to the switch/fuse is you want a quick fix...personally I like cleaner/professional way of tracing and fixing the original wiring....but I again have had my days...:ugh:
Yea, I'd like to figure out why it's not working, especially if it's cause for concern.

Thanks for your help and brainstorming! :thumbup:
 
#35 ·
Alright, here is the deal. Poor dc connections are a pain to find.
A test light requires power to light the lamp, a meter has a very low power requirement. I have been bit before assuming a dc circuit had power after seeing the voltage on a multimeter only to find the voltage disappeared when a load was applied.. So a test light is best in thus instance.

Two options here. Disconnect both wires to motor and remove fuse then measure resistance to the source wire ie ground location and + power location.

Other option temporarily run a jumper wire from negative of the battery to where the ground is for the motor and see if that fixes it.

Here is what I don't understand. How are you reversing the window? Typically on a dc motor the polarity to the motor is swapped to reverse the rotation via a switch so the negative would feed a pin on the switch and not direct to the motor.

If that's the case then negative of battery would go to the switch. Pm me for my cell if you need additional explanation or help trouble shooting.
 
#36 ·
Check out the wiring diagram on sunroofs for clarification...but yes, its reversed polarity...its a very simple switch...with the ground "bar" on top and 12v on bottom.

When the button is pushed theres a metal bar that hits the positive and in turn drives the motor that cooresponding(sp?) way...and vice-versa.

I'm just stumped to why the power is intermittant...I'll def. try the test lead.

The power is also run through the RAP relay, I will mess with that also.
 
#37 ·
Good deal then swap the suspect ground with a lead direct from the negative of the battery to confirm if it's the grounding circuit that's intermittent. When you tried the battery trick was that at the switch or direct on the motor?

If you disconnect wires upstream of the switch and replace with a separate bat that would eliminate an intermittent switch.

Keep us posted. It can run but it can't hide
 
#47 ·
Well your set Darek bc urs is black!