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MG MGB Technical - Turn key to start nothing happens

When I turn the key to start my 70 BGT nothing happens. I have a remote starter button that I attached directly to the starter and the car started right up. I think it is a faulty ignition switch but before I tear into the steering column is there anything else I should be checking.
LS Sheldon

Do you hear a "click" at the starter relay (it's silver "thing" - mounted next to the fuse box)?
Daniel Wong

Depends on where your remote starter button is connected, obviously, the fault will be back towards the ignition switch, wiring wise, from that.

1970 was the first year to have a starter relay, so a late 69 not registered until 70 wouldn't have one. As Daniel says if you have it should be a 'silver' box (or a black cube or cylinder if it has been replaced) by the fusebox.

With a starter relay the ignition switch puts out 12v on the white/red to the relay, which needs an earth on the black to operate. These wires should go to the W1 and W2 (85 and 86 if replaced) terminals in either order.

Check you have an earth on the black terminal when you have 12v on the white/red. If 12v on both the earth is bad. If 12v on neither then the white/red back towards the ignition switch is bad, check at the bullet connector by the steering column and on the switch terminal. If you have 12v and earth but you don't hear the relay click the relay is bad.

If the relay clicks, then 12v comes in to the relay on a brown, and goes out to the solenoid on a white/brown, on the C1 and C2 (30 and 87 if replaced) terminals, again in either order. Check you have 12v on both the brown and the white/brown when the relay is operated. If no 12v on the brown then that wire has an open or bad connection back towards the fusebox. If there is no 12v on here either then it is back towards the solenoid, and the interior lights and horn won't work either. If you have 12v on the brown but not on the white/brown then the relay is bad. If you have it on both then the problem lies in the white/brown between the relay and the solenoid.

If no relay then the white/red goes direct from the ignition switch to the solenoid.
Paul Hunt

"When I turn the key to start my 70 BGT nothing happens"

I think that's a design 'feature'..!

There's a bundle of brown cables coming up from the starter solenoid - two go to the alternator, one goes to the relay. I had problems on my 1970 GT, until I found that the wires had rubbed through (on the chassis rail) and were held together by the remnants of the wrapping. Worth a look?

Neil

Neil22

I tried the easiest first. Tapped the silver box nest to the fuse box a few times and the car started. I am not certain this is the culprit so I will go for a drive and try starting a few more times. Nice thing about MG if it does not start it is light enough to push and start. Motor cycle bump and jump. I will let everyone know what haappens.
LS Sheldon

The relay must have been the problem. No problem starting at all. The relay is sealed so there is no way I can look inside to see what caused the problem. The one in my car does not have the button. Rather safe than sorry, this is my wife's daily driver so I will replace it with a new unit.

Love quick, easy fixes.

Thanks everybody for your tips.
LS Sheldon

It's quite easy to get into the Lucas 6RA 'silver box' relays, just ease back the edges of the can from being over the insulating base. Not really worth it mind, if there is an internal problem.

But if just a tap fixed it I'd me thinking more of bad connections at the spades than anything internal, or possibly where the central spade is rivetted to the core of the winding. The former is just a matter of cleaning and possibly nipping up the spade connectors, the latter you may be able to fix with a pencil wire brush in a drill to get to bright metal and soldering.
Paul Hunt

This thread was discussed between 31/10/2009 and 01/11/2009

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