Auskartdyno

I have just resurrected the cruise control on my 82 ROW manual by working through wsm and a posted check list. It now works but when I engage it a central warning panel brake pressure warning is triggered. I can only reset it by disconnecting battery. If I do not engage cruise control everything is fine no warning. Brake hydraulics have been fully reconditioned with master cylinder stainless sleeved.
I have had a brake light warning light which I assumed was due to fitting of LED brake lights and have ignored.

Any ideas please

The Forgotten On

If you haven't replaced the pressure switches under the master cylinder with high quality replacements you should do so now.

Those two sensors are what activate the brake lights and send a signal to the cruise control, not the bulbs like in later years.

They have probably gone bad or shorted internally giving a current feedback to the warning system.

sendarius

IIRC, the cruise control senses voltage drop across the brake lights to determine when to shut off, or maybe it was current?
If, as you say, the car has LED brake lights, I would suggest swapping them back to standard filament bulbs to see if the problem persists.

Andrew Schauer

I can confirm that attempting to use LED brake light bulbs will cause a brake pressure warning when you engage the cruise control. I even tried some of the newer CAN bus style, which supposedly have similar internal resistance to a standard bulb. Same results, brake pressure warning each time the cruise control is engaged.

Andrew
1980 5-speed