1800: What is this red light ??!👀

[ChasesDragons]

Hello,
1971 P1800E. Can someone please identify this red light please? Its on the far right of the vehicle.

Regards

Edit: following good advice to show a pic!

[JP 1800]

Can you post a picture?

Likely a handbrake/ brake circuit warning light, however with out a picture it is just speculation

[JP 1800]

From memory that appears to be the handbrake/brake circuit warning light. Does the light stay on when the handbrake is disengaged. If so you need to check your brake fluid or reset the brake pressure differential switch.

[cassell]

Yes, that is the position for the handbrake warning light which also functions of a circuit failure warning if one of the dual circuits fails.

Yours is not the original lamp and has been replaced with an aftermarket lens at some time, the original Volvo one has the word 'BRAKE' in white lettering on the red lens.

It should extinguish when the handbrake lever is lowered via a trigger switch under the carpet there, if it remains lit it's likely that you have a failed circuit or the 'shuttle' valve switch has never been reset after a brake system bleed operation.

Hope this helps.

[c1800]

Double post.

[c1800]

“ Yours is not the original lamp and has been replaced with an aftermarket lens at some time, the original Volvo one has the word 'BRAKE' in white lettering on the red lens.”

The 1971 uses a different warning lamp than the later models, and does not have the white lettered word “Brake” on it. So what CD has is likely original.

-71 on the bottom of pic , 72- on the top.

[volvobysea]

If you are lucky it will be an easy fix to turn off this brake failure warning switch assuming it is not going out when you release the handbrake.
Just locate the brake master cylinder and the connection to the warning switch.
Carefully unscrew the sensor and remove it you may have to push the brake pedal to balance out the dual circuit braking system.
Refit the sensor and the light should now go out if it comes on again and stays on you will have a fault in one of the braking lines and it will require some further checking to identify where the fault lies.

Gavin

[Ron Kwas]

CD;

As Cassels has noted, either Handbrake away from its rest position, or difference in pressure between the two braking systems can supply the chassis connection necessary to light the indicator, as it is OR-tied. See: https://www.sw-em.com/OR-ing%20Circu...rake_Indicator

...then again, the switch at the Handbrake may be sluggish with age and simply need two drops of Deoxit lube/contact preserver. See: https://www.sw-em.com/Product%20Reviews.htm#Deoxit...determine which of the two sources of chassis connection is responsible for completing the circuit, and proceed from there...

Good Hunting!

[ChasesDragons]

Thank you so much for the advice again, to all.

I will check and lube the Hand Brake switch as advised and I will try to fix the brake failure warning via the sensors, as described....the brakes can be best described as "notional" on this car, functioning partly by hydraulics, mainly by prayers.

Warmest regards
U

[142 Guy]

If this is a 'new to you' car, be aware that if your rubber flex lines to the wheels are original, aside from cracking problems they can suffer from swelling which restricts fluid flow leading to various problems. Perhaps put that on your to-do list.

A 1971 with 4 wheel discs should stop smartly. If your investigation of lackluster brake performance involves brake bleeding be sure to follow the bleeding procedure set out in the factory service manual. There are 8 bleed nipples in the system and order does matter if you want to get the system bled before the cows come home. If you have a source of compressed air I recommend using a pressure bleed system to make things go smoothly.

If you have the brake warning light and you have poor brake performance my first step would be to check the brake failure system switch operation. You can remove the electrical contact from the H block that contains the pressure monitoring device and confirm whether the switch is good or bad. If the electrical contact operates correctly, you almost certainly have a pressure unbalance in the hydraulic system that needs to be fixed. If you need to do hydraulic system repairs, make sure to unscrew the electrical contact from the brake failure detection mechanism before bleeding the system. When there is a pressure unbalance there is a piston in the mechanism that moves off center allowing the little pin in the contact mechanism to drop down causing the warning light to illuminate. If you fix the hydraulics and restore equal pressure in the brake systems the piston in the failure detection mechanism will re center and likely chop the end off of the operating pin (not always; but, frequently).