Thanks for help so far, I have tried the mfu test. Beeps on pressing rear heater switch but won't react to front heater switch

 

Pushing the button should place a ground on the blue/purple wire which is pin 1 on the switch connector, or pin 19 of the MFU connector. Not sure which is easier to get at. If at the switch end, a voltmeter would read a plus voltage of some level (not always 12), which would drop to zero volts as switch is pushed and takes that point to ground.

 

I am unclear on what the "no beep" on the MFU test actually points to as the problem?

We already know that the front heated windscreen isn't working...,does a "no beep" on MFU test point to a specific cause?? How does it help pinpoint the problem?

Thanks guys!

 

If the MFU does not obey or respond to that input, it won't turn on the relay, which then applies power to the wind screens and the light bulb in the switch. I suspect that Rover designed the heated wind screen to only stay energized for a modest period of time, not constant while driving down the highway. This is a case were a small current is used to control a module controlling a larger current (relay) which then controls real amps (wind screens). See electrical wiring diagram attached to post 2 of this thread.

 

This will show you how they work, and from that comes the knowledge to test them: http://www.autoshop101.com/forms/hweb2.pdf

You'd need to know the pin outs for the particular relay, but that's in the ETM.

 

Hey guys. Quick question....when I test voltage at the connection at the cowl, how many volts should I be seeing on the truck side of the connector?

TIA!

Andy

 

First post, first land rover. Just got my 2001 Disco 2 SE last week. It's exciting!


Dealing with the same thing. I get no power at the 7 and 8 40 amp fuses in the front box, either with the dash button on (lights up) or the AC set to defrost.
I'm wondering if my BCU "knows" if has a heated screen? Thinking I have to take it to a dealer to run Testbook and see.
Is this just asking for trouble?
Also I can't find a diagram of which relay(s) is involved. I have the service manual, but am still downloading the 500mb RAVE pdf. Not sure what the difference is…

Thanks!

 

You wouldn't happen to have the numbers for those LED replacements, would you?

 

Ah, the RAVE helps. Also looking on the inside of the fuse lid (who knew?).
Turns out I have no relay in the spot for the heated windscreen, so I think that may be the problem.
Or at least a start.
Now I just have to figure out where to get a new one. I'm foreseeing a need for a good Landrover parts source… East end of Toronto anyone?

 

I have a 2004 Discovery S. Can anyone provide the specific relay (part number) that goes into the engine compartment fuse box for the heated front screen (position R8 30 amp I believe)?


Thanks