Another "what's this?" thread - inside the dash version

[ski wagen]

As part of doing several things, including removing old wiring from now-obsolete things such as A/C, alarm and stereo, I have removed the fresh air blower and related HVAC components from inside the frunk for access. The photo below is taken behind the furthest gauge to the driver's left, and I'm hoping someone can help me confirm/identify a few things. It's on a 1979 SC.

First, where the green arrow is pointing, I think this is a deleted relay for the seat belt warning system -- am I correct?

Second, where the the blue arrow is pointing, I think this is the turn signal/emergency flashers relay - am I correct?

Third, what might the black box with the white plug above the red arrow be? Some old aftermarket alarm system component? It is really tucked back in an obscure corner.

Finally, the Bentley manual suggests there should also be a windshield washer relay in there just beside the missing (seat belt warning?) relay plug-in spot, but there is no trace of any additional relay or connection for it. If missing, then where would the windshield water relay otherwise be (I've located the intermittent wiper relay elsewhere - is that in lieu of the one that should be here, or in addition)?

Thanks in advance for insight/answers.

[Mark Salvetti]

The red arrow is pointing to the rev limiter relay. A surprisingly obscure component. It isn't mentioned in the factory manual or the Bentley, only the Porsche 1978 Service Information brochure.

It's obscure until it fails, because it typically leads to intermittent engine cutouts that can be maddening to track down. It works by taking pulses off the tach, and at redline it cuts power to the fuel pump.

You can disable it by pulling the white connector. The car still runs, but you lose the rev limiter.



Mark

[ski wagen]

Thanks Mark! I never would have guessed that one.

[Mark Salvetti]

You're welcome. I only know about it because mine was one of the rare failures.

Mark

[Uwon]

You are correct on the blue arrow. Turn signal flasher relay. Just lies there loose amongst all the wires.You can confirm by touching it with the turn signal on.
Johan

[Trippyloaf]

You are correct on the Green Arrow - seatbelt warning relay. I'm trying to get mine working right now.