Why Won't My Rear Windows Work???
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Camel Trophy
Joined: Nov 2015
Posts: 3,560
Likes: 834
From: Staten Island, NY
Some great info there, Deputy. Checked things out this morning, and unfortunately it seems to be pointing to the BCU.
Fuses 13 and 29 are good; they were checked and changed with the new fusebox. However, there are no hot terminals in the relay socket (checked to ground). Which of course means that jumping terminals 30 and 87 doesn't do anything.
I left the key on for 5 minutes just for good measure -- no change.
Is the BCU upstream or downstream from relay 3?
Fuses 13 and 29 are good; they were checked and changed with the new fusebox. However, there are no hot terminals in the relay socket (checked to ground). Which of course means that jumping terminals 30 and 87 doesn't do anything.
I left the key on for 5 minutes just for good measure -- no change.
Is the BCU upstream or downstream from relay 3?
Camel Trophy
Joined: Oct 2016
Posts: 4,867
Likes: 1,410
From: Michigan
Did you check for power in the drivers compartment fuse box. You say you changed the fuses, but did you check for power at them? Power runs directly from the fuse to relay, so if you have no power where #13 and #29 terminate in relay socket...it would have nothing to do with BCU. BCU just supplies ground for relay activation, that's all. Me, l'm thinking you have a mega fuse out, inside the engine compartment fuse box. Check for 12 volts at the fuses inside, across both tabs of #13 and #29. If they are hot (12 volts) and you have no power at relay...something is seriously wrong with the wiring behind fuse box.
EDIT, getting mixed info from the electrical manual. One area says #29 terminates to IDM and #13 goes directly to relay, but is controlled by IDM. What relay position are you checking? Maybe you have a different year fuse box and they used R4 instead of R3...?
EDIT, getting mixed info from the electrical manual. One area says #29 terminates to IDM and #13 goes directly to relay, but is controlled by IDM. What relay position are you checking? Maybe you have a different year fuse box and they used R4 instead of R3...?
Last edited by The Deputy; Oct 24, 2020 at 04:30 PM.
Camel Trophy
Joined: Oct 2016
Posts: 4,867
Likes: 1,410
From: Michigan
Actually, you could just run a temporay jumper wire, 12 volts, from one of the fuse tabs to relay position terminal that feeds power to window motors...and windows should work...if window motors are in working order. Then we'd know a little more.
This shouldn't be that hard to diagnose, it's like were missing something simple.
Actually, on my wifes 03 l had an issue where the wires underneath the engine compartment fuse box (which feeds all power to drivers compartment fuse box) had rubbed through...and it never blew the fuse. It rubbed through at such a slow pace, l assume, that it didn't blow the mega fuse. It's easy to pop fuse box loose and check.
This shouldn't be that hard to diagnose, it's like were missing something simple.
Actually, on my wifes 03 l had an issue where the wires underneath the engine compartment fuse box (which feeds all power to drivers compartment fuse box) had rubbed through...and it never blew the fuse. It rubbed through at such a slow pace, l assume, that it didn't blow the mega fuse. It's easy to pop fuse box loose and check.
Last edited by The Deputy; Oct 24, 2020 at 04:05 PM.
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Camel Trophy
Joined: Nov 2015
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From: Staten Island, NY
Solved. Fusible Link #6 in the main fusebox.
I'm sure I changed this piece, and tested continuity on the new one, but apparently this was the problem all along. The sunroofs also work now too. Still weird that the front windows worked just fine.
Thanks for all the help on this one.
I'm sure I changed this piece, and tested continuity on the new one, but apparently this was the problem all along. The sunroofs also work now too. Still weird that the front windows worked just fine.
Thanks for all the help on this one.
Camel Trophy
Joined: Oct 2016
Posts: 4,867
Likes: 1,410
From: Michigan
Front window switches share power supply through drivers compartment fuse box with BCU, fuse #34. And #34 is not associated with FL #6. It relies on FL #1, #5 and #8.
Glad you got it figured out. However, if you believe you changed/checked this FL before and it was good...still might be a good idea to pull engine compartment fuse box and inspect wires and terminal plugs. There's a strip of metal, part of inner fender well, that rubs wiring harnesses and causes issues.
Glad you got it figured out. However, if you believe you changed/checked this FL before and it was good...still might be a good idea to pull engine compartment fuse box and inspect wires and terminal plugs. There's a strip of metal, part of inner fender well, that rubs wiring harnesses and causes issues.
3rd Gear
Joined: Aug 2023
Posts: 3
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Discovery 4 issues
Fuses #13 sends power to the rear window lift relay (R3) in drivers compartment fuse box, #29 througg IDM. Pull relay, turn ignition to position 2, check for two hot sources in relay terminals, if you have two hot terminals, fuses are both good. So, that would lead us to the BCM, which l believe sends the ground signal that activates relay. If the fuse box is loose/hanging out, back probe the ground circuit of the relay with a ground wire you've made up. If the relay clicks and windows work...BCU may not be communicating with new IDM or BCM is bad. The manual says that if you swap out a new IDM (which you did, it's built into fuse box)... you must leave the key on for 5 minutes afterwards, so the BCM and IDM can communicate and get to know one another, turn key off...then turn back on.
lf fuse box is mounted, pull relay and just jumper terminal 30 and 87 of the relay. If windows and sunroof work...again...it's looking like it's a BCU issue.
lf fuse box is mounted, pull relay and just jumper terminal 30 and 87 of the relay. If windows and sunroof work...again...it's looking like it's a BCU issue.
DEPUTY
you sound very experienced. have you ever come across a similar situation to this.? it's going to break me
Discovery 4, 2013
NS Rear window switch not working (from master switch too OSF)
replaced NSR Switch - not working
replaced NSR module - worked for 5 minutes
replaced OSF switch - no difference
replaced OSF module - no difference
removed & reconnected NSR module - works for 5 minutes again, and continues to work for 5 minutes every time you remove & refit module but no longer
All other windows work fine
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