Hi all

I have a weird problem I was hoping someone may have come across previously.

Took the EL 6cyl for its annual roadworthy and the mechanic pointed out to me that the brake lights...all 3... operate when the parkers are turned on and not at all when the brakes are applied

Even weirder...they worked last weekend when I was checking my boat trailer lights

The rear parkers do not come on at all

I have traced all the wiring and cannot find anything obvious.

I was thinking of simply changing the brake light switch and headlight switch...$50 and lots of swear words hurled about...but thought I would ask for further advice before I just start willy nilly throwing cash at the problem

Is there anything else I should be looking at before I tear my dash out?

Any advice greatly appreciated.

Craig

have you checked/disconnected the trailer wiring?

start by checking inside trailer plug for loose wires that may be shorting together make sure harness from trailer plug is not touching on exhaust or split etc.

then check all fuses with a test light - earth one end of test light - power both ends of fuse when circuit on ie. ignition fuses will only have power when ignition on - tail only with lights on etc.

do dash lights work if so not headlight switch -
check tail relay in fuse box

have you changed globes may not have been working for a while ??
if so make sure correct globes ie.approx. 12v21w/5w double contact -

ignition on use test light on stop switch power on one side nil on other side until you press brakes then power both sides if so switch ok.

Have traced all wiring but did not pull trailer connector apart...could be the issue.

All dash lights fine.

All fuses and wiring to fuse box ok.

All globes check ok.

I will have to try the test light tomorrow afternoon on your suggestions.

Thanks for the advice. I'll post the results.

Cheers.

Hi,

You may have 2 separate problems that look like 1 strange issue. The brake light switch is a very common failure. Test it with a multi meter, and if it seems OK try a test globe to be sure. When it is known working, take out both tail light globes. You say the trailer socket is good, they can also be the cause of many problems though. With both globes out test it again. Look at the number plate light and the central brake light. If they are both working as they should have a good look at the removed globes. It is rare, but a filament can break and reconnect to another pin inside the globe. Are both globes twin filament ? Many strange things can happen if a single filament globe is forced in. ( cruise doesn't work at night and engine keeps running when you turn it off with your foot on the brake )

Thanks 96ELGi and others.

Tried bridging the brake light switch

Removing globes

Rechecked all globes just in case

traced wiring again just in case

rechecked trailer loom and connector again...just in case

swapped relays over..........all to no avail

I notice a few comments on various forums about the brake system going through the cruise control system, and this vehicle has an inoperative cruise control system fitted

I suppose the only two places left to look are at the possibility the headlight switch is rerouting power incorrectly or whether the inoperative cruise control system is doing something to the system.

All brake lights continue to work continuously when parkers and lights are turned on...just as the front parkers do...but rear parkers are non existent as are brake lights when parkers/lights are turned off...which at least means the rear parkers are not wired into the brake circuit

Is it possible the previous owner may have plugged the wires onto the headlight switch incorrectly? I've never seen the connectors so do not know if this doubtful proposition is even possible.

It is almost time for me to pay for a romantic weekend away for an auto elec and his missus

If it worked ok before you fitted the trailer plug and now it doesn't, I would guess to say that there is something wrong with the wiring to the trailer plug.

craigies1 Post subject: Re: Brake lights operate through parker light controlPosted: Sun Mar 09, 2014 5:13 pm

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Joined: 29th Dec 2012

Ride: EL Fairmont

Location: Shoalhaven
NSW, Australia
Thanks 96ELGi and others.

Tried bridging the brake light switch

Removing globes

Rechecked all globes just in case

traced wiring again just in case

rechecked trailer loom and connector again...just in case

swapped relays over..........all to no avail

I notice a few comments on various forums about the brake system going through the cruise control system, and this vehicle has an inoperative cruise control system fitted

I suppose the only two places left to look are at the possibility the headlight switch is rerouting power incorrectly or whether the inoperative cruise control system is doing something to the system.

All brake lights continue to work continuously when parkers and lights are turned on...just as the front parkers do...but rear parkers are non existent as are brake lights when parkers/lights are turned off...which at least means the rear parkers are not wired into the brake circuit

Is it possible the previous owner may have plugged the wires onto the headlight switch incorrectly? I've never seen the connectors so do not know if this doubtful proposition is even possible.

It is almost time for me to pay for a romantic weekend away for an auto elec and his missus
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Anything is possible !!
Take a photo of the connections and disconnect the trailer wiring completely from the main harness in case connections are bridging together.

Brakelight feeds to cruise control not thru it to cancell the cruise and also causes cruise not to work if it doesn't have normal brake light circuit .

Did you check for power with a test light at brake switch as brake lights wont work when bridged if no power in first place ?

You stated all was working the week before is this fact or you thought they were which would rule out somebody altering headlight switch wiring ,if this is correct points to wiring shorted together.........

If you remove the 2 normal stop/tail globes does eye level light come on with park lights ?
do brake lights come on if tail light relay out??

plug trailer socket into car socket and see if lights work as you said they did ... if they do check socket on car

Problem partially resolved.

Anything is possible alright...just not what I thought.

Borrowed a working headlight switch and can rule that out. 1 hour well spent.

After looking at the workshop manuals wiring diagram I went back to the tail lights and decided to work forward methodically.

I don't know how I missed it first time around but the LHS stop/park light had distortion in the spring steel contacts. It was shorting itself out. I only realised it when I shook it and said "what the F... is wrong with you you dirty..." while glaring at it The contacts touched each other. 2 minutes and some manual pressure and all of a sudden my brake lights do not come on any more when I turn the parkers or headlights on

The brake lights however do not work at all I might just buy a new brake switch tomorrow given the commentary on the forum on just how unreliable they are...or maybe I could just borrow one...worked today with the headlight switch

And all this with my boat trailer plugged in to the circuit

Thanks guys for your input...it helps me get my mind out of its own box

bridge out the brake switch - if works then switch is.......

All fixed...thanks guys

Was an unfortunate combination of shorting contacts in the LH stop /tail light, a wire crushed sometime in the distant past leading into the RH stop tail, and a $12.95 brake switch from Moto Parts.

Thanks heaps guys...the wiring on those circuits is now perfect