Brake fluid light 740 GL

  • Thread starter Thread starter les.watson
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les.watson

1988 740 GL Brake fluid light on the dash is lit when the engine is running.
I have checked for brake fluid leaks also the brake fluid level which are
both O.K.
The only other thing I can think to cause the problem is there must be a
pressure switch somewhere on the brake fluid system or its a faulty relay.
Any advise on what action to follow.





Les
 
les.watson said:
1988 740 GL Brake fluid light on the dash is lit when the engine is running.
I have checked for brake fluid leaks also the brake fluid level which are
both O.K.
The only other thing I can think to cause the problem is there must be a
pressure switch somewhere on the brake fluid system or its a faulty relay.
Any advise on what action to follow.
Click to expand...
Check the float is working properly. It's in the reservoir cap. mebbe the
float is sinking or the wiring has gone bad. should be two wires on the cap
top.
 
No wires on res cap on my model.
No wires anywhere near res cap.



Les.
 
From a point at sea, to the circles of your mind, this is les.watson:
No wires on res cap on my model.
No wires anywhere near res cap.
Click to expand...


Then you don't have a brake fluid warning light.

My '87 GLE has no such light. It has a brake circuit failure light, a
parking brake light, and (if I had ABS) an ABS malfunction light, but
none for brake fluid level (some 740s did).

If you are certain the light you are seeing is brake related, then
whatever it is needs investigating. It's possible one of the two brake
circuits has failed (usually a failing master cylinder), but I would
expect to feel a softer brake pedal with this. There is not
necessarily a leak with this, though sometimes brake fluid can soak
the carpets around the pedal.

Just to clarify, the order of lights on my dash (taken from the
handbook - not all are relevant) from the extreme left is:

1. Diesel glow plug
2. Blank
3. ABS malfunction
4. Lights
5. Turbo-diesel high boost
6. Engine oil pressure
7. Battery charge
8. Overdrive engaged
Milage reset button
9. Headlight main beam
10. Brake circuit failure
11. Parking brake
12. Bulb failure
13. Screen wash fluid level
14. 4th Speed disengage
15. Seat belts
16. Blank


--

Stewart Hargrave

Faster than public transport


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les.watson said:
1988 740 GL Brake fluid light on the dash is lit when the engine is running.
I have checked for brake fluid leaks also the brake fluid level which are
both O.K.
The only other thing I can think to cause the problem is there must be a
pressure switch somewhere on the brake fluid system or its a faulty relay.
Any advise on what action to follow.
Click to expand...

If the pedal has become soft I would suspect the master cylinder. There are
two brake circuits and if they don't have equal pressure the brake failure
light will come on. The brake failure/pressure difference valve could be
bad.

I had my light come on and was able to fix it by just bleeding the brakes.
YMMV


Brick_0
 
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