4 way flasher problem

[Danno]

Back lights flash front lights don't when flasher button pulled. Bad flasher? Do the turn signal and 4 way flashers use the same flasher unit...(for troubleshooting)?

 

[Blueoval71]

Back lights flash front lights don't when flasher button pulled. Bad flasher? Do the turn signal and 4 way flashers use the same flasher unit...(for troubleshooting)?

Are you saying this happens when you use the hazard switch, turn signal switch or both? There should be a separate hazard and turn signal flasher.

Technically the hazard flasher overrides the signal flasher by tying the left and right together. The front and rear are controlled at the contact in the turn signal switch.

Start by swapping the hazard flasher with the turn flasher and compare results, but they are cheap so I would just replace them both. Many of the signal issues I repair are caused by the hazard switch. It is rarely used and the contacts oxidize thus losing contact.

 

[Don C]

There are two different flashers, but they both just have a single wire that runs to either the turn signal switch or emergency flasher switch, so if the flashers work on the front the emergency flasher is good. The common element for the turn signals, brake lights, and emergency flashers is the turn signal switch, as all of them run through it. The turn signal switch is prone to problems, from broken plastic pieces to dirty/corroded contacts, and would be where I would start.

 

[Blueoval71]

There are two different flashers, but they both just have a single wire that runs to either the turn signal switch or emergency flasher switch, so if the flashers work on the front the emergency flasher is good. The common element for the turn signals, brake lights, and emergency flashers is the turn signal switch, as all of them run through it. The turn signal switch is prone to problems, from broken plastic pieces to dirty/corroded contacts, and would be where I would start.

All correct.The flasher is simply an auto reset circuit breaker. The reason I recommended starting at the flasher is because they are likely old and you will experience current drop through an old or faulty flasher. The front/ rear, left/right are independent wires which make contact via the turn signal switch. The contacts often develop different amounts of corrosion (resistance). I had a similar situation in my 91 Mustang two months ago and replacing the flasher solved the problem in my case. The drop across the flasher when combined with the resistance from the corroded contacts caused the issue in my case. The worst that will happen by replacing the flashers is that you will be out $6.00 and they will work another 20 years. It is most likely the turn select assembly, but it will only take a few minutes to swap the flashers.

 

[Don C]

I agree, sometimes we can never find a single point of failure, but when you start adding up all of the high resitances across the flashers, the switches, several slightly corroded connectors, old fuses, and even the bulb bases all of it adds up to a problem. Just one of the challenges of owning classic cars.

 

[midlife]

There are two different flashers, but they both just have a single wire that runs to either the turn signal switch or emergency flasher switch, so if the flashers work on the front the emergency flasher is good. The common element for the turn signals, brake lights, and emergency flashers is the turn signal switch, as all of them run through it. The turn signal switch is prone to problems, from broken plastic pieces to dirty/corroded contacts, and would be where I would start.

All correct.The flasher is simply an auto reset circuit breaker. The reason I recommended starting at the flasher is because they are likely old and you will experience current drop through an old or faulty flasher. The front/ rear, left/right are independent wires which make contact via the turn signal switch. The contacts often develop different amounts of corrosion (resistance). I had a similar situation in my 91 Mustang two months ago and replacing the flasher solved the problem in my case. The drop across the flasher when combined with the resistance from the corroded contacts caused the issue in my case. The worst that will happen by replacing the flashers is that you will be out $6.00 and they will work another 20 years. It is most likely the turn select assembly, but it will only take a few minutes to swap the flashers.

Damn it...you took the words right out of my mouth.

 

[Danno]

Back lights flash front lights don't when flasher button pulled. Bad flasher? Do the turn signal and 4 way flashers use the same flasher unit...(for troubleshooting)?

Are you saying this happens when you use the hazard switch, turn signal switch or both? There should be a separate hazard and turn signal flasher.

Technically the hazard flasher overrides the signal flasher by tying the left and right together. The front and rear are controlled at the contact in the turn signal switch.

Start by swapping the hazard flasher with the turn flasher and compare results, but they are cheap so I would just replace them both. Many of the signal issues I repair are caused by the hazard switch. It is rarely used and the contacts oxidize thus losing contact.

No, only when the flasher button is activated. I know there are 2 separate flasher units, but was wondering if the are interchangeable for troubleshooting purposes. The turn signals are ok. I will probably just replace both anyway, precautionary. Thanks for all the answers.

 

[midlife]

Yes, the flashers are interchangeable for trouble-shooting, but the e-flasher is typically capable of handling more current than the turn signal flasher.