Shift lock and Brake lights inoperable.

[PalmerWMD]

Just today as I was pulling out of a Firestone (Got Alignment), I noticed my shift lock wouldn't release and on a check my brake lights were inoperable.

I figured no bog deal I'd just get to that one shop I know and replace fuse (it had happend once before and an easy fuse replacemtn fixed it).

Last time it happened, when I stared the engine with the brake pedal depressed and apparently it burned out a fuse.

Anyway this time no burned out fuse was to be found or teh one thatw as replaced wasnt responsible as the condition has not been addressed.

The shift lock release and the brake lights are on the same circuit.

Any thoughts?

Fred..

[PalmerWMD]

BTW:

Not sure if I made that clear at all in the preceding post:

All fuses check out OK.

Fred..

[greg_atlanta]

It's a switch/sensor at the top of the brake pedal. About the size of a spark plug. Has a little white plastic button that moves in and out as you depress the brake pedal. But it doesn't last forever.....

Dealer should have the part, around $10-15. Not too hard to replace if you're flexible. I think you have to remove panel under dash to get to it.

[Q451990]

That's my guess too. Had a brake switch failure at about 110-120K. Should cost less than $10 from your local dealer or $3.91 from Joe. I noticed a "pop" in the stereo when I'd press the brake pedal sometimes (more in cold weather) in the months before it failed. I guess the contacts were getting dirty.

I think that switch crosses over to a lot of Nissans so you should be able to get it at a Nissan dealer too. Just practice your hand signals

Heath

[elwesso]

Definitely brake switch...... The shift lock system works through the brake switch....... It requires a VERY flexible person to get under there...... I had to lay backwards on the seat with my head in the footwell to get it at it, or i was half out the car (i perfer that method, the other way rushes too much blood to the head :puke )

[PalmerWMD]

Me and Joel) couldnt find that switch..:oface.

BUT, it turned out teh replacemtn of fuse was done at the wrong fuse at first so on a retry the problem was fixed.

Fred...

[elwesso]

FYI...... The switch is at the top of the brake stalk........ Take the brake pedal stem all the way to the top..... from there you should see what looks like a metal plate, and two little nubs with boxes right next to each other...... One is the ASCD brake swich, and the other is the stop lamp switch.......

[Q451990]

Fred,

Have you determined what's taking out the fuses? You'll probably find charred tips in at least one brake lamp socket. This only gets worse, and the real problem is that you may not know about it while driving - and then get rear ended! The dash warning disappears when the whole circuit is dead.

Heath

[PalmerWMD]

Yes I noticed it the dash warning doesn't come on.

Too bad I am not in ATlanta just got back from a T3 trip (lenghty write-up to follow as soon as I have time).

Fred...

[PalmerWMD]

Actually it only seems to blow when someone is starting teh car with the brake pedal already depressed.

Fred...

[Q45tech]

Check all the rear bulbs and sockets.

[PalmerWMD]

Right now the problem has worsened the fuse will blow on the first application of the brake.

gsr779 (Joel you met him dennis) and myself are looking at rear sockets.We also noticed a LOT of condensation in the third brake light.Maybe thats responsible.

It has rained very heavily in Atlanta and here, when the car was in those locations.

Fred...

[PalmerWMD]

We just disconnected the third brake light and thougth we had found teh cilprit since on disconnecteing that we actuatyed teh brake lights again and again w/ no brakage.

But the litmus test is starting up car with foot on brake and that <did> blow the fuse once more.

Now looking at the otehr brake lights.Do we have to disconnect wiring or is it ok to just takle out to the bulbs to try to find which one is the one ?

Fred..

PS: I ahve a lot of 10,15,20 a fuses here (15 is right size but 20 has blown before)

[PalmerWMD]

Anotehr update:While I was in here typing Joel had disconnected all brake lights (all 3) and it still blew the fuse.

Soooo a short somewhere deeper?Any good places to look next?

Fred..

[Q451990]

I'd disconnect the connectors, not just remove bulbs. If you have a shorted connector, it'll take the fuse without the bulb. You mentioned condensation in the 3rd light... you might make sure that it doesn't have water in the connector that's shorting.

Heath

[Q451990]

If you're down to the point where anytime you press the brake pedal the fuse blows, I'd also try disconnecting the shift lock mechanism, and try taking the brake lamp switch out of the circuit and just shorting out the pins to complete the circuit. It's possible that the switch is shorting internally?

Heath

[PalmerWMD]

It mostly happens if the car gets started w/ the foot on the brake pedal.

Sometimes, it happens even just when pushing the brake pedal but not always but often enough to make a fuse vlowing frequent.

Its a 15 a fuse, have a 25 a in there now, hoping it'll last me a few days ( dont like to drive w/o brakelites) and not daring to go higher.

Fred...

[PalmerWMD]

Well its gotten worse once more.Now <any> application of brake will blow the fuse at first try.

Fred..

[PalmerWMD]

Heath:Yes we tried with all lights disconnected as well and still blew fuse.

Fred..

[Q451990]

This gives you the best chance to find the problem. Intermittant problems are a real pain to trace...

Did you try taking the switch out and then shorting the pins in the connector? I don't remember if the switch is switching 12V or ground, but an internal short could be causing it... Also, have you eliminated something in the shift lock mechanism yet?

Does your car have remote start? I know it's heavily modded but I'm not sure if that's on the list or not. If so you might check to make sure that the brake switch input to the alarm (that kills the car while it's running after remote start) isn't getting back to ground somewhere.

Heath

[Q451990]

Yes we tried with all lights disconnected as well and still blew fuse.

By lights you mean at the harness or just pulling the bulbs.

One other thing you might try is removing the warning sensor - I suppose it could short to ground too.

Heath

[Q45tech]

Check the rear bulb electronic current sensor left quadrant under the snap on trim piece [trunk release mechanism in center].

If this is not problem remove rear seat and check wiring harness [by moving things around slightly] ..........there were a few problems years ago with heavy person sitting on left rear side and some how pinching the harnesses from objects falling behind and under rear seat.

[PalmerWMD]

forecast is gonna stop by w/ voltmeter and assorted toolslater.

Fred..

PS: my wipers stopped working too and my HICAS light came on.

[PalmerWMD]

This is what we treid so far:

disconnected all rear connectors again to include the distributor(?) in the middle under the plastic cladding--> still a short.

Also disconnecetd some suspicious aftermarket wiring (towing brake light grr)Also still shorting.

Now chekcing the brake switch over/under the brake pedal

[PalmerWMD]

The brake switch is not the culprit either (checked by forecast via volt meter).

THere is one more distributor/connecter left before the next step is teh main wiring harness under the dash.

For that job I probably will have to come back to T3, cuz the dealer will charge an arm and a leg and I am not sure I trust the local independents enough for that job.

Fred...

[PalmerWMD]

Never underestimate a man that has rebuilt Q engines:

After ripping the car ( to include some of upholstery a part, Dan found some corrosion on the distributor under the rear seats.

BUT that wasnt it.

When I told him I probably wont make it to T3 for weeks to come he rigged a set-up and restored my brake lights and wipers by running a new wire.

He is pretty sure the problem is a splice or controller under the dash, but this way I will have functioning brake lights until I make it to T3.

Amazing!

Fred...

[elwesso]

I may have to come down there and have forecast take a look at my car!!! mmmmmm, people who know lots about the Q....... soooooo much knowledge :drooling:

[Q451990]

Does your car have (or did it have) an aftermarket alarm? If so that would be my first place to start checking. It'll be interesting to see what the problem is...

Heath

[LAQ]

i had a similar problem, but my brake lights work. the shift does not. i wonder what it is... going to replace the fuse anyway tomorrow..

[forecast]

I may have to come down there and have forecast take a look at my car!!! mmmmmm, people who know lots about the Q....... soooooo much knowledge :drooling:

wes that would be a bad idea. I know wiring, I know my way around a torque wrench, but as to why a Q would have low power ... that's a little out of my league. I just don't have the tools or experience to diagnose performance problems.

My own Q is light on power (the compression is fine, so it's probably something electronic - I guess injectors, but could be MAF, temp sensor, or even plugged cats.) Recently my Q has really started sucking the gas - I'm seeing under 12 MPG - and I don't know why.

Now, if you determined an injector needed changed or a knock sensor needed replaced, even complicated jobs like guides or cats - I can do that in short order.

Fred's happy because his brake lights work again, but I didn't really discover why he has the problem. The brake light switch is a full current switch, fed directly from it's own fuse.

The wire runs in a harness in a long inverted U, up to the top of the dash, across to the left, down pass the transmission computer and back. At the rear seat the harness goes through a connector.

All I could determine was that after the brake switch and before the connector under the rear seat there is a short.

Fred's rear seat connector is badly corroded, with a few wires 90% or more bad, however the brake light line was ok. For a really clean car, this was suprising - someone must have spilled a "big gulp" coke down there years ago.

A number of items in the dash want to know when the driver hits the brakes; the ABS control, the power steering control, the HICAS unit, the shift lock control. (and TCS & full active units but Fred doesn't have those, though I assume the wiring harness includes these points) Each one of these represents a splice off the brake line and an eventual connector.

The only way I know to diagnose this is to open the dash up and begin disconnecting the various units and checking the connectors.