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MG MGB Technical - Now the flasher problem is just down right weird!

I went out and checked the wiring to the hazard switch on my 71B. Everything was connected correctly. I tested it with the radio and antenna disconnected - it worked. I reconnected the battery and it stopped working on the left side signal and the ignition light started flashing again. I removed the radio power and it started working ok again. I put the antenna on (not connected to any power whatsoever) and it started doing the same crazy thing again. I disconnected the antenna and tried the power - same thing. I disconnected both - worked ok. So first thought was a bad stereo. I left it disconnected and tried the hazard switch - nothing at all. Hazards didn't work and neither did the signal. I turned the hazard switch back off and the signals started working ok again.

I then disconnected the power to the stereo from a green wire and moved it to a brown wire (so the memory wire and the power wire were both hooked to brown). I reconnected the power and it started acting screwy again. I removed both green wires from the hazard switch and touched them. The signal indicators worked both ways with the radio connected.

I never disconnected the signal stalks from the harness during the dash & center console refurbishment.

This is just weird!

(Previous post)

Posted 08 May 2009 at 04:03:28 UK time
I just installed a new dash (well, recovered the old one). I've got everything hooked up and it all seems to work fine except for the right side turn signal/flasher. The left side works fine. When I move the switch for the right flasher, the lamps don't flash, but the ignition light does (I can hear the flasher unit clicking). I tried the hazard switch and nothing happens when I turn that on. I thought that if the switch were bad that neither flasher would work.

Any ideas what I hooked up wrong?

Robert



Paul Hunt
West Midlands
United Kingdom
paul.hunt1@blueyonder.co.uk_http://www.mgb-stuff.org.uk/ Posted 08 May 2009 at 15:40:19 UK time
Sounds like you have some crossed wires. Does the dash tell-tale light for the right side? Or only for the left? If only for the left then double check the wire colours and tracers on the turn switch and the dash harness, being careful to observe the difference between the green of the green/red and green/white indicator wires and the light-green of some other wires.

If the ignition warning light flashes when the ignition is *off*, then the problem is probably in the wiring of the hazard warning switch. A 2-wire turn signal flasher unit shouldn't flash unless there are two and only two 21W indicator bulbs (plus the tell-tale) in circuit. Less that two and it shouldn't flash (just light the remaining bulb if only one is working) ir it will flash very fast and probably burn out the unit if there are more that two. A 2-wire hazard flasher unit should flash with anyting from one to four bulbs connected. Clicking when the corners don't flash indicates (pun not intended) to me that it is the hazard flasher you can hear flashing, and not the turn signal flasher.

The hazard switch should have two green wires (one from the fusebox and the other to the turn flasher unit), a green/white and a green/red (to the flasher bulbs), a light-green/brown (from the hazard flasher unit), and possibly a light-green/purple (to an additional hazard flasher tell-tale bulb). With the hazard switch in the off position the two greens should be connected together to connect the fused ignition supply to the turn flasher, all the other wires should be isolated. With the hazard switch on the two greens should be isolated, and the other three or four wires all connected together.

An additional check is that when you first operate the turn switch the selected side should light up straight away, then after a short pause start flashing off-on-off-on. When the hazard switch is operated there is a short pause, then all four corners start flashing on-off-on-off.



Robert Rushing
St Louis
Posted 08 May 2009 at 23:43:56 UK time
Thanks Paul! I don't know why I always forget to say what I have (71B). I don't think it's the turn signal switch or wiring since I left that in tact when I pulled the dash and center console. I bet I screwed something up with that hazard switch. I'll pull it out and recheck everything.

Robert


Robert Rushing

A minor quibble, but in the original post you say the right side has the problem, in this repost you say it is the left.

If you saying that when you removed the two greens from the hazard switch and joined them together everything worked as it should, but when the two green are on the hazard switch you get the problem, then the hazard switch or how your wires are connected to it are definitely the problem.

Note which terminal each wire goes to, remove the switch entirely from the dash and the wiring, and test for continuity between each terminal and every other terminal first in one position then the other. Translate that to which *wires* are connected together in each position of the switch and it should only be as I posted earlier i.e. "With the hazard switch in the off position the two greens should be connected together to connect the fused ignition supply to the turn flasher, all the other wires should be isolated. With the hazard switch on the two greens should be isolated, and the other three or four wires all connected together." If you get continuity between any other combination, such as a from either green wire to the red/green, red/white, light-green/brown or light-green purple (if provided), in either the on or the off position, then that is the problem.

Paul Hunt

Yeah, I screwed up the original post - the problem occurs with the left blinker while the right works fine.

I have to wonder if I have some kind of short or something else connected wrong and that it's trying to ground through the stereo. I find it strange that when I connect the antenna or the power to the radio, the problem returns (of course, I figure that the hazard switch is definitely bad since it doesn't work at all whether the radio is connected or not). I just don't get why the right side will work fine with everything hooked up, but the left doesn't work and the ignition light flashes - what could they have in common that would cause that?!?

I'll play around with it some more this evening and post what I find.

Thanks Paul!

Robert
Robert Rushing

Robert,

I don't suppose you have cross fitted the left blinker and ignition warning bulbs?
Regards
Roger
Roger T

I thought about that Roger, but I can get them to work when I connect the green wires together. The ignition light works correctly when I start the car, it only starts going crazy when I try the blinker lights.

I guess I could just quit using turn signals like most of my fellow Americans...

Robert

Robert Rushing

Well, the hazard switch is definitely bad; but I think the main problem was coming from the cigarette lighter. It was shorting against something. As soon as I removed it, things worked ok (except for the hazards). At least the blinkers are working right now!

Robert
Robert Rushing

This thread was discussed between 12/05/2009 and 15/05/2009

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