Indicator Fault?

[Richard71]

Hello All,

 

Still tearing my hair out with teething trouble since having my car recently MoT'd.

 

The latest and most serious issue I'm now addressing is the indicators...….I fitted an electronic flasher relay, new switch and complete new harness.

When Indicating to the "right" all is well, no problems, when Indicating "left" all other components begin to dim, the fuel pump runs slower and pulses in synch with the flasher relay and very little (if any) light emitting from the indicator bulbs. While testing/fault finding I've so far burnt out two relays.

I've by-passed or bridged out the switch to eliminate that as the culprit, so do I have a short circuit along the green/red wire somewhere and if so, can anyone offer a means of detection???

 

Thanks in advance,

Richard.

[Waldi]

Looks like you have a short when the right side is activated; voltage drops, other components dim.

I would start by disconnecting read and front indicators, right side, that is easy.

If no luck, disconnect wire from switch etc.

Waldi

[barkerwilliams]

There is no way the fuel pump and the lights should be electrically connected, but they are all interconnected through the earth return. I would start by looking at the near side rear of the car right in the corner of the rear lamps where the earth from the lamps and the fuel pump should be connected to an earth tab at floor level. If the earth is disconnected or the tab does not electrically connect to the chassis I| would expect "unusual" electrical behaviour depending on the path the current takes to find an earth. I found it beneficial to run a heavy duty earth from that connector through the cabin onto the battery to chassis bolt.

 

Alan

[Richard71]

Thanks for the replies......when I fitted the new harness I took the precaution of fitting extra heavy duty earthing to the rear lamp assemblies, I've already disconnected the front & rear indicators one at a time and tried the switch, the problems persists, looks like it'll be a long weekend trying to sort this.

 

Richard.

[lightningburns]

Richard,

 

As you have burnt out 2 flasher units I would discount an earth issue, a high resistance earth would not damage flasher units, they are also usually designed to flash at a constant rate no matter what load is on the output so would still try and flash even if the output is shorted with other components . When you say you have fitted a new harness is that a complete car wiring loom, is it as standard or do you have extra fuses and relays incorporated, do you have a hazard flasher.

 

Regards,

 

John

[RobH]

The tests required to find the fault depend on the year of your car, Richard as the hazard-flasher relay may be before or after the indicator switch as shown in these diagrams:

http://www.advanceautowire.com/tr2506.pdf

(Note that these show Gn/Rd as being on the RHS for only the '72 model. I don't know whether that is a mistake or not )

 

Since your flasher relay is electronic you could first try connecting a separate bulb direct to the flasher on the LHS (with the Gn/Rd disconnected of course) and see whether that behaves itself. That will confirm whether the fault is downstream of the flasher.

 

You could then continue by removing all of the LH flasher bulbs and the dashboard tell-tale bulb and do a resistance check to earth on the green/red wire (assuming that is the LH feed) with it disconnected from the flasher switch. It should be open circuit. If not, pull off the corresponding feed to the hazard relay (or hazard switch depending on which model you have) and try again. That will tell you whether the short is in the feed to the bulbs or to the hazard circuit

 

If its the bulb feed at fault you next need to separate the feed to the front and rear lights and re-do the resistance check on each.

 

If the fault clears when you remove the connection from the hazard circuit, the next move must be to check the connections to that i.e. are the wires on the right pins.

[Richard71]

Richard,

 

As you have burnt out 2 flasher units I would discount an earth issue, a high resistance earth would not damage flasher units, they are also usually designed to flash at a constant rate no matter what load is on the output so would still try and flash even if the output is shorted with other components . When you say you have fitted a new harness is that a complete car wiring loom, is it as standard or do you have extra fuses and relays incorporated, do you have a hazard flasher.

 

Regards,

 

John

 

Thanks John,

 

It's pretty much a standard harness, no extra relays or fuses.....the strange thing is, everything was working fine until a few weeks ago, the car was collected on a recovery truck and despatched to have 4 wheel alignment carried out, have the horn sorted and finally MoT'd, when I collected the car I found immediately that indicators no longer worked.....drove it home anyway and now I'm trying to solve the problem.

 

Richard.

[peejay4A]

I wonder if when sorting the horn out they disturbed the indicator switch. Have the steering wheel off, remove the horn ring and the escutcheons and have a good look around.

[lightningburns]

Richard,

 

That seems odd, what did the garage do to get the horn working, was it wiring or changing the horn itself, my bet would be as you should have two horns it was the wiring, and also to pass an MOT the indicators should have been working, unlikely to have gone wrong on the few yards from the MOT bay to be parked.

 

John