North American Turbocoupe Organization

PRC Light Only on Under Heavy Throttle
atengnr Offline
Today, the light for PRC is off and wont come on, except under heavy throttle.

I was working under the under over the weekend, near this electrical component mounted on the passenger fender that has 2 vacuum lines that go to the turbo. What is this??

Any ideas on why the PRC died?


natmac3 Offline
Sounds like the electrical component you describe is the factory boost control solenoid (BCS).

Not sure where to start on diagnosing the PRC issue, but it clearly has defaulted to the Regular setting and only switching to Firm as it is supposed to under Accel, Cornering, and Braking.


vegas_ss Offline
Senior Member
Most likely the auto/firm switch if the prc's are acting like they are in auto mode when switched to firm. Try flipping the switch a few times... I was usually able to get it back to firm after a few tries, replacing the switch fixed it

If you press on the brake pedal hard and/or turn the wheel quickly that will trigger the prc's from auto to firm, that would point more towards the switch too as all the auto/firm functions work except the firm override.
1987 TC, 5sp, Boport Stage 3 Head/2.1 Cam
1996 Impala SS

TurboCoupe50 Offline
Posting Freak
Also if you exceed 80mph it will switch to firm...

99% chance it's the dash switch, flip it a few times as suggested... They can be taken apart and the contacts cleaned(pencil eraser)and will work just like new, but you better be good at chasing small springs and contacts...
1988 Turbo Coupe331 AOD

1972 Comet GT

1969 Fairlane Cobra 428CJ 4-Speed

86XR7auto Offline
Not to hijack the thread. But my PRC light works like it cornering, braking, above 80mph.... But the car does not firm up. I inspected the front struts, everything looks fine. Is there a way to manually make the car be firm? When I play with the switch nothin changes...

86XR7 in pieces...old time [email protected] 88TC stock Red RHSC [email protected], 01 Z71=Nice winter ride, 01 CVLX w/HPP wifes ride!

Pete D Offline
You can manually turn the valving in the struts and shocks to firm then unplug the actuators.
Pete Dunham


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