Brake warning light

[MEZZZ]

I found that 3 prong plug (left hand side) disconneted under the Passenger seat yesterday and plugged it in to see what happened to see if it was the Fuel pump relay or not.

My brake warning light worked fine evertime I used the E-brake untill then and now it won't turn off. Now when I unplug the connector the Warning light will not light up even when I use my E-brake even though it worked just befor.

I took out my seats to recover them yesterday, (got one finished, my hands are killing me )and noticed the same thing disconnected under my passenger seat. I also had the connection going to the e-brake unplugged. I plugged everything back in and my brake warning light stays lit. If I unplug the 3 prong, the brake warnign light goes on and off like it is supposed to.

I looked at the wiring diagram in the service manual but cant make heads or tails of it, (I am a novice to all of this). Can anyone tell me what this 3 prong entails? I am concerned if the light is on all the time it may be a sign of a more serious issue.

[geoyam]

The 3 prong plug is for the Brake Warning Lamp Check Relay which is mounted under the passenger seat. It's function is to verify that the Brake Warning Lamp is functioning. The Brake Warning Lamp serves two purposes. It tells you if you have a pressure differential problem in the hydraulic brake system via the Brake Indicator Switch and it tells you if your parking brakes are on.

The Brake Warning Lamp Check Relay comes into play when the ignition switch is turned to the on position. It verifies that the lamp is not burned out. It is suppose to go out when the engine is started. If the lamp remains on, there are 3 possible reasons. Your parking brake is on, there is a problem in your hydraulic brake system or the relay is bad. Generally if you remove the plug from the relay and the lamp goes out, it indicates that the relay is bad.

I had the same problem with my 77, The relay coil burnt out. The relay (Part# 25230-N4700) is no longer available from Nissan. The Brake Warning Lamp Check Relay for the 1978 models was still available from Nissan as of November 2006 (Part# 25230-79906).

The bad part is that they are not interchangeable between model years. If I remember correctly the relay for the 77 model was wired up as a normally open relay, and the relay for the 78 model was wired up normally closed.

I ended up having to pull the 78 relay out of its can and wiring it up to the contacts in the 77 relay can. Works great now, but if you don't have the skills to do so, it's not for beginners.

Sorry for the long explanation, but hope it helps.

[MEZZZ]

The 3 prong plug is for the Brake Warning Lamp Check Relay which is mounted under the passenger seat. It's function is to verify that the Brake Warning Lamp is functioning. The Brake Warning Lamp serves two purposes. It tells you if you have a pressure differential problem in the hydraulic brake system via the Brake Indicator Switch and it tells you if your parking brakes are on.

The Brake Warning Lamp Check Relay comes into play when the ignition switch is turned to the on position. It verifies that the lamp is not burned out. It is suppose to go out when the engine is started. If the lamp remains on, there are 3 possible reasons. Your parking brake is on, there is a problem in your hydraulic brake system or the relay is bad. Generally if you remove the plug from the relay and the lamp goes out, it indicates that the relay is bad.

I had the same problem with my 77, The relay coil burnt out. The relay (Part# 25230-N4700) is no longer available from Nissan. The Brake Warning Lamp Check Relay for the 1978 models was still available from Nissan as of November 2006 (Part# 25230-79906).

The bad part is that they are not interchangeable between model years. If I remember correctly the relay for the 77 model was wired up as a normally open relay, and the relay for the 78 model was wired up normally closed.

I ended up having to pull the 78 relay out of its can and wiring it up to the contacts in the 77 relay can. Works great now, but if you don't have the skills to do so, it's not for beginners.

Sorry for the long explanation, but hope it helps.

That helps emmensely, thank you very much. I wish the service manauls were written for an idiot like me to figure out so easily. I never started the car as I had other things I was working on as well as the seat replacement but will start it up tonight and check to see if the light goes out. My guess is the relay is bad because the ebrake seems to function normally when it is unplugged from the relay. Thanks again.