Rear defrost locking My doors???

[Jrock]

Ok- So I did a search and didn't see anyhting for this one. I got in my 1998 Disco this morning, hit the rear defrost window button (top left side button of steering wheel dash) and my doors locked. button lit up and all doors locked. None of the other buttons on that side (rear fog, volume +/-) or any side did this, only the rear window defrost button. I'm gathering something is shorting out some where....??? Any thoughts out there or any one else have this one happen to them? ----1998 Disco I LE just passed a full inspection today here in PA with flying colors.

[Savannah Buzz]

The wiring diagram in the RAVE shows that trucks with alarm system share the MFU (multi function unit) for some related functions (timer) with the rear defrost system, which also uses it. There's always fuses, water on connectors from sun roof leaks, and ground points that have come loose and forced electrical current to find other ways to the battery. The ETM (electrical troubleshooting manual) and a test light will be helpful.

[Jrock]

yeah,

I've got the rave and Haynes, I'm digging through that now for the shared power points in the controller. I'll start tracing wires and grounds tomorrow.


I did have my rear drain tubes clog over the summer. I did pull the H.L. and fixed all of them while I was at it. What a Pain...

[Disco Mike]

Also do a visual inspection of the wire harness from the body to the tail gate to make sure no wires are chaffed.

[tweakrover]

Ha ha mine did that when I first got it, the fuses for the mfu were burnt out, replaced them and its been good ever since.

[Savannah Buzz]

Once again Mike has a good idea - that cable bundle is shared by both the locks and the defrost, connector C415. So a squashed rear door cable could be the ticket. Looked at drawing in RAVE, connector number appears in drawings for locks and defrogger. Pix attached.

[Jrock]

thanks guys,
I'll be pulling this apart tomorrow to start chasing wires for the fault. I'll let you know what the out come is.

Thanks for the PDF.

[tweakrover]

Hello anyone home, I just said I had this issue!! Check your fuses for the mfu, it controls a bunch of stuff, door locks, dome lights, alarm, defroster, rear wiper, the owners manual specifically states when dealing with electrical issues the check the fuse associated with the problem and the mfu fuses, 12&13 I think.

[Savannah Buzz]

I'm sure he will check the MFU fuses first before looking at the wiring.

[Jrock]

yes tweakrover,

I'm home... and as a good shade treer that I am...the fuses will be check first thing and before anyting else.

Thank all. i'll repost the findings tomorrow.