Topic

Permanent +ve and switched earth used to be a popular config for horns etc. Good old Brit engineering!

Hah

My guess is that the casing will be connected to the supply negative inside the unit. This isn't a problem if you wire it with the + on the -, unless the casing of the motor is touching the vehicle chassis, then you would have a direct short.

I guess I'll see next week. Odd how all the other posts on the Freelander swap are all positive and seem so simple. I've had zero luck with the electrics in my car so I'll be sure to test before the plug comes off

I think that a bench test with a battery would be my choice, then a meter on the loom to see what goes live and when it does it. What could possibly go wrong chaps?

I'm still tempted to shrug this post off and just fit it, I've never heard anyone else have problems, but then my luck and electrics.....

A bench test and meter on the loom for sure. I've got some test leads with clips on after a fog light nightmare so will pre fit in situ with those before the plug finally comes off and anything get soldered up

Right then.

I have found the problem and come up with a workaround.

The problem is, as I mentioned, that the MGF setup is switched earth and the Freelander switched live.

On the Freelander, the printed circuit board is earthed through three supporting pillars to the casing. This means that the black wire into the motor is earthed to the casing.

Two of the posts are visible in this picture





As the MGF uses that black wire as the live feed into the motor, obviously the casing will be live. (as well as the wiper arms/brackets)meaning that any attempt to bolt the unit onto the car results is a blown fuse.

Solution is to isolate the pcb from the casing.

I used a dremel to grind the posts back, and enlarged the holes in the pcb slightly.
I then inserted three small pieces of plastic in between the posts and the circuit board, and glued them to underside of the PCB. Tested and NO connection between the black wire and the casing. Result.
I then re-fixed the pcb in place and put the motor back together.
Tested and working fine, casing not live.

Fitted into the car and working OK. RESULT!

Thing is, I have just taken delivery of a pukka MGF motor (second hand). Anybody need a wiper motor?

Mine arrived this morning. I wont have time to fit it for a couple of days but I',e lopped the plug off and done some bench testing.










I can't for the life of me make get the case live, that being said I don't know enough about electronics to know whether or not I should be able to testing it with a battery and multi meter. So far looking good. Will update you when I get it to the car

Check for connectivity between the black wire and the casing.

Tried that, I only have continuity through the wires, black, red and blue. Nothing from the case

Ok cancel all the above, I was testing against the black part of the case. Against the gear housing I have continuity and it registers 11.24 volts. Bugger

Yeah, That's what I found too.

My mod is working OK, but it's a long way from a straight swap.