MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB Technical - GT heated rear Window

HELP PLEASE Its that time of year. Been through archives. Got me crazy now. Original '71 HRW glass (orange colour "wires"). Soldered new chunky wires before install to side tracks. Earth goes via soldered terminal to main body. Supply is switched with old supply line to relay, new supply is direct from battery with line 20A fuse. Readings: 12v on glass side tracks, earth is perfect to glass side track. With 12v supply and earth disconnected is near on 1ohm. Connected up again with +60/60 ampmeter in 12v supply line no deflection, I reckon should see 14/18 amps! To test Should I try directly to battery?
Richard Evans

Hi.

Is it possible that you have a good connection from the HRW earth to the tailgate, but the tailgate is not electrically connected to the body ?.

Try a voltmeter between the earthy side of the HRW and the main bodywork. If it reads 12v (HRW on) your problem is as described above.

Don
Don

Hello Don
Thanks for feedback. The earth is directly to the main body, not via hinge, similar to 12v supply.
Richard

With everything connected and turned on check for voltage on *both* spade terminals on the actual glass, which following a recent MGOC mag article on replacing the glass I think they have, not just the tails attached to the glass.

12V on both means the earth is bad. Check again where the tail joins the earth wire and the earth wire connects to the body.

0v on both means there is a break or bad connection back towards the 12v supply. Check again where the tail joins the loom, and each connection back to the relay, and each side of the relay contact.

12v on the 12v terminal and 0v on the earth terminal (check with an ohmeter or against a known 12v source) means the circuit is broken between the two spades, which if the spades are on the glass means the main printed track is broken on one side or the other :o( But if you are reading about 1 ohm between the glass wires then hopefully the problem will lie elsewhere :o)
Paul Hunt

This thread was discussed on 01/01/2005

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.