brake warning light - relay bad

[AnthonyG]

happy days. I finally found why my brake warning light was on all the time. after fixing and replacing nearly every part of the system, it ends up the coil in the control relay melted, leaving it stuck on.

the relay was the one under the passenger seat. good thing it didn't ignite when it melted, though then it would have been the prior owners problem...

I've obtained a new relay from autozone, so i'll be designing a replacement circuit to replace the relay. (since this relay is no longer available...)

yay

[AnthonyG]

update. cheap relay is cheap. got a good waterproof relay from amazon, and a mount for it. also got an additional relay to make the lighter jack turn off when car is off. (because i like it that way)

and ill be addign a second lighter jack for accessories on the back of the armrest facing toward the cargo area.

I like my electronical gadgetries.

[AnthonyG]

ok. got parts from amazon. I'll post part numbers in next post, if it works in the car.

pic taken with iphone so not the greatest...

also of note. the relay is small enough that it could be fit inside the old relay can. gutting out the old relay and soldering in the new one looks doable. then reclose the can and no-one would ever know it wasn't original...

[AnthonyG]

ok it worked. i'll be trying it out to see if it melts or catches on fire...

part 1, relay:

12 VDC Waterproof Relay SPDT 30/40A with Metal Bracket

(http://www.amazon.com/gp/product/B000PHLQJW/ref=oss_product)

wire harness:

12 VDC 5-Pin Relay Socket Interlocking Style

(http://www.amazon.com/gp/product/B002QAQVIC/ref=oss_product)

the old relay wire colors ----> new wire harness colors ----> relay pin numbers

black ---- red wire + white wire ----- 85 + 87a

yellow ---- Black ----- 86

green/white ---- Blue ----- 30

I' try to get better pics once i find my camera. and this is for a 1976 280z. Knowing nissan, they probably changed how its wired every model year, if not evey month...

[silver02tt]

on my 76 the relay color wire is solid black- solid yellow- soild blue- white with blue-white with green so how do I wire these color to the new relay

[AnthonyG]

tough question without seeing the relay. if you could confirm what is connected to what color in the relay you could redo it for this instance

in my pictures you can see the color of the wires on the old relay, and see where they connect inside. the setup they used was energized means light off.

post pictures if you can

[SteveJ]

on my 76 the relay color wire is solid black- solid yellow- soild blue- white with blue-white with green so how do I wire these color to the new relay

Don't worry too much about the wire colors on the relays (old or new). Only the coil and normally closed contacts are used.

I am attaching a picture of how the relay should be wired to the old connector. The colors match the main wiring harness colors according to the wiring diagram for a 76, courtesy of Phil, aka Blue. If you get everything lined up right, you'll have no problems.

Let me know if you have any questions.

[Captain Obvious]

My new 280 does this... Brake warning lamp stays on all the time.

I'm assuming this is a common issue and this relay is where I should start my investigation?

[Zed Head]

It could also be the brake pressure differential switch, either stuck or indicating low pressure in one half of the brake system. How do the brakes work on the car? Does the light go off if you pump the brakes?

[Captain Obvious]

It could also be the brake pressure differential switch, either stuck or indicating low pressure in one half of the brake system. How do the brakes work on the car? Does the light go off if you pump the brakes?

Yeah, I'm sure there are other things that could cause the light to come on and I've done no investigation at all at this point. I bought the car, drove it a couple hours home, and parked it in the garage. The brakes felt fine the entire trip.

The light came on when I pulled the parking brake when I stopped for gas and then never went back off when I was done. I wiggled the parking brake handle and switch there on the trans tunnel, but other than that, I've done nothing.

I was just figuring that if everyone else's relay was going bad and causing this problem, then that's probably what's wrong with mine.

[kilaueacarlos]

Thank you everyone who posted on this topic. I couldn't get by the safety inspectors because the warning light was on constantly. Disconnecting the brake balance switch and the parking brake had no effect so I was at a loss. As soon as I read that there is a relay and where it is located I was on the way to driving again.

 

Indeed the relay was fried. A trip to the parts store and with a lot of looking by the parts guy, we came up with a workable relay and after half an hour of fabing a suitable wiring harness, my '77 280Z is back in business.

 

Thanks SteveJ and AnthonyG for taking time to aid the community!

[SteveJ]

It's posts like yours that inspire me to help. Thank you for letting us know we done good.