Contemporary parking light / blinker lamp stays on

[SCOBRAC]

I posted this problem once earlier looking for a direction and got some great replies, but I'm still chasing an electrical gremlin in my Contemporary built in 1988. The car has almost 20 years and 23,000 trouble free miles. The last 5 with me. I mention this as there has been no history or systemic issues with the car.

I was out for a nice drive last month, a few hours and a hundred and fifty miles maybe. About half way throught I parked for several hours and I think I left my marker lights on. When I got back to the car and fired it up the ammeter went way over and stayed there for almost 45 minutes and gradually settled down. When I got home I noticed the front left marker light was illuminated in the bright mode, or having both the turn signal and the marker filiments on and would not shut off.

All the lamps work in the car, headlamps, marker lamps brake lamps. The right front and rear blinker operates as it should but the left does not flash front or rear. Not surprizing since the front blinker is already illuminated.

I posted the inquiry here and got a number of good replies icluding grounding issues, lamp and bulb issues, shorting out of lamp sockets, flasher replacenment and lamp socket grounds. I dismantled the turn signal control module and the relays are working as it should, tripping the relays left and right. Both relays seem to be working the same way and have a crisp clean stike between the contacts.

I have been slowly running down the potential causes one by one and have narrowed it down a little. All the grounds are good, (at least the ones I can find) including the grounds at the lamp fixtures everything seems to be as it should be with the exception of the lamps being on. Ive replaced all the bulbs, headlamp swith and the flasher with no change in the problem.

I have seemingly isolated the main source of the problem or perhaps main symptom. There are 2 wires going to the front left turn signal as well as a ground, a solid white wire and a solid green wire. If I disconnect the just solid white wire at the junction under the hood the marker lamp filiment goes off (dimmer of the two filiments). If I disconnect just the green wire both filiments go off.

This suggests to me that the green wire is being fed from a source other than the turn signal control module and is feeding back through the system, and disconnecting it from the lamp shorts the circuit Is this logical? I didn't build this car and to be honest troubleshooting electrical isn't my strong suite.

If you own a Contemporary have you had a similar experience, or even if you have owned another marque and had a similar problem, how did yo fix it. I ask because at this point I am about to start chasing individual wires under the dash and it will be a messy job. Any help would be appreciated.

[xlr8or]

Sounds like the flasher relay to me. That green wire should be connecting back to the relay to control the front blinker. Check the output on that contact with a volt meter with the wire disconnect from the relay and see if it pulses power when you turn on the blinker for that side.

[SCOBRAC]

I guess I am under the impression flasher (#550) is the relay. There is a headlamp relay but it controls the high/low on off. I will look into it, thanks. Wouldn't the bulb pulse and the flasher be operating if the voltage were changing?

[xlr8or]

That's the idea but it sounds like the relay is stuck in the wrong position giving constant power to the light.
I believe in most setups the blinker switch controls which output on the relay is powered and the flasher just makes it pulse. Since the right side works normally you can assume the flasher is working correctly.

[SCOBRAC]

Interesting. I will check that. Thanks.

[strictlypersonl]

Are you using some kind of tail-light relay?

This doesn't make any sense... There is normally no power source that doesn't come through either the brake switch or the flasher unit.

[SCOBRAC]

I wish I were more electrical saavy, I don't see one. As noted I didn't put the car together. I really don't think the early Contemporary cars did. It has to be going through the flasher unit. (Doesn't it???) It's a pretty simple concept. Contemporary specified a #550 flasher but I'm wondering if I got a bad unit when I replaced it. It flashes the right side but not the left, which seems like it could be caused by power feeding back through the system form somewhere. I would have thought disconnecting the lamp and essentially inducing a short circuit within the short circuit would allow the left rear blinker to flash, it doesn't. The exception to this would be if the original short was closer to the controller.

The lights being on / staying on screams bad ground someplace. Every person I have posed this question to says bad ground. My own experience tells me 90% of all elecrical problems with these cars is a ground related problem. I will triple check them. Something which occurred to me was the turn signal switch may have developed a fault.

Is it logical that I can reverse the turn signal switch connections to change the left blinker and right blinker orientation? The switch doesn't care which side of the system it's operating... If I do this the left blinker position becomes the right, the right becomes the left. If the left blinker becomes operational and the front right parking lamp / blinker filiments stays lit, it is very possibly the turn signal stalk assembly. My assembly looks not unlike something out of a VW beetle, it should be easy to fix or replace.

Unfortunately Contemporary's assembly doesn't cover malfunctions or troubleshooting operations. After 18 years of trouble free service I guess I can see the wisdom in that.

[strictlypersonl]

Take a look at your tail lights. You will have a ground and two other wires on each side, correct? (I'm assuming that you've got a single bulb in a rectangular light.) It that's the case, there's a relay somewhere that takes two signals (one from the brake light switch and one from the signal switch) and translates it to a single signal to the brake/signal filament at the rear light.

The early Contemporarys may have used a Lucas relay to do the translating.

It may look like like the silver box on the firewall in the foreground.

[SCOBRAC]

Indeed the tail lamps are a single bulb type (1157) and rectangular and they are each grounded to the frame. I've got very limited for electrical under the hood except the starter selinoid, voltage regulator and the ballast resistor (a leftover from the points ignition system I left in place for a period look). The car has no blower / defroster, windshield wiper motor or related hardware (Hey it's California). The only other electrical under the hood is the wiring harness to the headlamps, alternator and fan.

The Contemporary Assembly Manual makes no reference to such a relay box. It identifies the wiring harness as a "late model GM" which means it might be circa 1980-1985. It does identify the directional light controller as a Volkswagon unit and it seems to be operating properly, the relay housings are clear and the relays operate as they should. This suggests the switch is not the issue and confirms my guess about the turn signal stalk / switch being vee dub.

I'd like to thank all who chime in, I'd hoped someone who'd had the same problem might drop by with a easy fix. I know you are all busy supporting your families as well as your addiction as I am, but I'd particularly like to thank strictlypersonl who has a personal interest in many hundreds of Cobras as well as a life. Thanks to all.

I'll be running down the potential faults as time allows. It's been over 105 degrees all week and the sun hits the new garage until about 8:30 here. As much as I'd love to bust out and test everything that might be wrong getting quality garage time has been tough. I'll update you as I know more. I will be out getting another flasher unit tonight and will put it in tomarrow, and run down a few other leads tomarrow.

Thanks again.

[ROUSHAC]

Michael,

Don't take offense. Sometimes it's the obvious that gets overlooked. Hopefully, this is it.

Check that all the bulbs are in their socket correctly. If in "backwards" both filaments will burn brightly.

Good luck!

Cheers!
Dave

[SCOBRAC]

None taken. I will reinspect the bulbs too... It seems curious it would just happen but anything is possible. How or why would the leads be hot in this scenario?

[ROUSHAC]

Good point, Michael. I missed that.

Hope you get it solved soon. Electical problems are the WORST!

Cheers!
Dave

[SCOBRAC]

sorry this is a stupid problem... I'm a little baffed on how a bad ground can create a condition where the power is on, but I am assurred it can, so It might be possible the bulb can cause this. Several people have suggested a shorted bulb can do it, I just wonder how. Something to do with with the position of the relays maybe?

[REDSC400]

This is a baffling concept. However, please rest assured that with a bad or weak ground in a single wire circuit, some strange things can happen. I had weak headlamps and direction lights that had both filaments lit. It was a weak or poor ground. The circuits were "feeding back" on the positive side to a ground on a different circuit. This was traced back to powder coating on the frame grounding point that was acting somewhat as an insulator.

ERA has an auto wiring primer that explains all this and also explains all the various components and how they work in the Cobra. You may want to ask Bob Putnam of ERA if he can grant you access to the ERA wiring primer.

[SCOBRAC]

Oh man, I've heard about the secret ERA knowledge but I assumed most of the stories I'd heard about the stuff there couldn't be true, it was so amazing. Is there really a section about how the 289 FIA cars differ from the 427 cars? I hope you haven't voided your warranty by telling us

I've had bad grounds which made my lights dim, it's part of the reason I'm baffled by my present situation. I will most certainly be checking them all again.

[RACER X #99]

Mike, I have a copy of the Contemporary wiring diagram. Send me an e-mail and I will try to help you out with the problem. No guarantees but I don't like troubleshooting on line.
Roger D

[xlr8or]

The wiring primer from ERA is available on the website at:

http://www.erareplicas.com/427man/wiring/index.htm


There is a link there as well about troubleshooting blinkers and brake lights.