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MG MGB Technical - another electrical dilemma

I have a chrome bumper 74
Last week the radio and wipers began to work sporadically, at that time I also noticed the tail light and side marker lights were not working. The headlight did work. I jiggled wires and removed and replace the fuses and the radio and wipers appeared to begin working, but the lights continued to stay off. I replaced the headlight switch but the tail and side markers continued to not work. I jiggled wires, ;unclipped and reclipped the wire connections under the dash but still no sucess.During this time I would start the car from time to time,but the last time it wouldn't start. I had power to the starter silnoid but that soon was lost. At this time the gas gauge, wipers and headlights work. The directional lights also work. When trying to start the car nothing happens, not even clicking.I would appreciate any suggestion on where to look in order to get the car started and the electricals back on. Prior to not starting there appeared to be power to and from the new switch when it was in the on position
rick baranyi

Sounds like you have a loose wire(s).

Only advice i can give is to chech all connections for tightness and clean -- clean up any and all of the grounding points, (where the black wires are connected to the body).

A wiring shematic would help to identify what wire is supposed to do what. Just take some care if you leave the battery connected. A volt/ohm meter comes in handy.

Trouble shooting ain't as much fun as skeet shooting but you can learn a lot more.

Have fun.
glg

On a 74 (CB at least) the radio and wipers (and washers and heater fan) run off the ignition switch accessories position via their own in-line fuse. The tail and side marker lights run off the top two fuses, one fuse per side, but from a single red/green from the main lighting switch. This switch also supplies the instrument lights, if these were OK it isn't the switch. If there was no clicking when trying to start the car check the white/red from the ignition switch (sound familiar?) to the starter relay, and the ground at the relay. Given the problem with the wipers etc. too I'd unplug the connectors by the steering column and check all the pins and correctly located. I have known these get pushed out of the back of the plastic block so they are only making contact at the tip, and movement can easily break the connection.
Paul Hunt

Also, go simple and be sure the fuel pump hot wire has not become dis-connected. Had it happen on a drive few weeks ago. No clicking so I looked under car and white wire was hanging loose.
J.T. Bamford

I have traced the red/white wire refered to by Paul Hunt. It goes to a black box which is located above the radio. There are 8 connections at this box. Would someone please advise me what this box is for and what color wires come out of it. I have power on the red/white wire to the box but cant't find a red/white wire coming out.
Does the red/white wire change to another color and go to the starter relay?
rick baranyi

That is the seat belt thingy aka bum detector. The start wire comes out on the yellow/pink to the solenoid - as long as all the switches that also feed into that box are in their correct state for cranking.
Paul Hunt

This thread was discussed between 11/05/2003 and 15/05/2003

MG MGB Technical index

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