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MG MGB Technical - Directionals don't work

I hit a pot hole and now my directionals don't work. I got a new flasher, but that didn't work. So I checked the voltage of the green wire going into the flasher and it showed 1.7v. It was varying between 1.5 and 1.9v. Any I ideas? I'm thinking maybe a problem with the instrument voltage stabilizer, but I don't know where it is. Also the wiring diagram shows a bullet connector between the stabilizer and the flasher, but I didn't find that either.

-Steve
Steven J. Korotky

Steve. First, we need to know what year your car is. The directional signals very depending on model. Later models, those with a hazard switch, have the power to the turn signals going through the hazard warning light switch. Earlier models, not having the hazard warning lights, are wired differently. Knowing the model year also helps us find the appropriate wiring diagram for that model.

As to the instrument voltage stabilizer, I am not aware that it is a part of the turn signal system. Again, knowing the model year of your car would be a good thing.

Les
Les Bengtson

My car is a '68 BGT. In the Bentley book, its wiring diagram #3. I've tried to trace through the diagram and it looks like the green wire comes from part #64, bi-metal instrument voltage stabilizer, then through a connector and then to the flasher.

In the car, I tried to follow the green wire, back. But it goes into the harness within a few inches and I can't find the connector or stabilizer.
Steven J. Korotky

Wiring diagrams are available at http://www.advanceautowire.com click on "stock schematics" The diagrams are easy to read and enlarge.

The turn signals are not wired through the voltage stabilizer. Only the fuel and temp gauges are wired through the stabilizer depending on the year.

Common problem is dirty, corroded contacts in the hazard switch. Try turning the hazards on and off with some vigor to possibly clean the contacts in the switch. If that doesn't work, then use your meter and start with the connections to the hazard switch and work your forwards or backwards along the circuit until you find the fault. After cleaning connections, use dielectric grease to prevent future corrosion.
Kimberly

Steve. I find that my 68GT is better suited to using the 69 wiring diagram in the Bentley manual.

But, as Kimberly writes, the hazard switch is the most common problem as the wiring for the turn signal goes through it. A quick check is to turn on the hazards--if they flash, you have power to the switch. If not, look for power going to the switch.

Les
Les Bengtson

I agree that the hazard switch is the most likely cause of the problem, especially with the voltage on the green at the hazard flasher being so low.

However the hazard switch uses a different voltage supply for the hazards (a brown wire that is always hot with its own in-line fuse), so even if they work it doesn't follow that the voltage for the turn signals is reaching the switch, as that comes from the green circuit i.e. fused ignition.

The hazard switch in the off position joins two green wires together, so see if you have 12v on *either* of these. If on one but not the other, then the switch is the problem. These tend to be used so rarely that tjhe grease hardens and can actually act as an insulator. Flipping the switch back and fore can act as a temporary cure, but failing that you can dismantle the switch in a poly bag (to catch all the bits), dig out the old grease and put in a bit of fresh stuff - whatever you have to habd that you use on the car.

If there isn't 12v on either green wire then something has become disconnected further back towards the fusebox. In the Leyland Workshop Manual both the 67/68 and 68/69 wiring diagrams show the green wire feeding the hazard switch going through a 2-way bullet connector quite close by, then going all the way back to the fusebox, although Bentley shows it 'daisy chaining' off the voltage stabiliser before going back to the fusebox. This will just be using the voltage stabiliser as a convenient connection point (the turn signals don't use it as such) but you can say that if the fuel and temp gauges continue to work then the 12v supply *is* reaching the stabiliser, so the disconnection must be between there and the hazard switch.
Paul Hunt 2

Steven,

When I had to fix mine the other day, it was the bullet connector under the hood on the right side. On mine there is a three bullet connector, and if I remember correctly it had white wires. This is in the area where the connections are made for the part of the harness that goes under the car. However, I think this connection feeds all of key-on components and is driven from the ignition switch. So, more than just the signals should have failed if that is the case.

Charley
C R Huff

does anyone have a diagram showing the hazard switch layout for a '68 BGT? Also, has anyone ever seen a diagram that shows the way the wires are bundled in the harness and the actual location of the connecters?
Steven J. Korotky

Steve, Did you print out diagram 7 in the link Kimberely suggested? Diagram 7 was correct for the 68 GT I used to own. I'm posting a scanned image of the signal and hazard lights blown up from diagram 7.

I don't know of a diagram of the wiring and bundling and lay out. The single connector in the green wire between the hazard switch and the and the signal flasher should be behind the console at the end od a pigtail harness that connects to the hazard switch. Other connectors for signal and flasher lights are under the hood near the fuse box, in front of the radiator under the shut panel and in the boot area. There are some under thhe dash but I don't know the locations.

Clifton

Clifton Gordon

Steve, I should have said there are several connectors behind the console, some of them are for the hazard and signal lights. Use the wiring diagram to identify the hazard/signal related connectors.

Clifton
Clifton Gordon

Thanks everyone.


The Hazard switch was it. I flipped the switch back and forth and then the directionals worked. Now its time to get the Hazards working.
Steven J. Korotky

Steve

It is possible to take the hazard switch apart and clean out the accumulated hardened grease and crud. This might be all the fix you need. See the archives for recommendations on the process. One important one is to do the disassembly in a plastic bag, slowly, so as not to lose any parts.

HTH

Larry
72BGT
Larry Hallanger

This thread was discussed between 30/12/2007 and 03/01/2008

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