wrhopcraft

Is there a diagnostic procedure for the Turbo Control Unit? The car is a '91 3.3T. I had the seat out, cleaned all the pins on the connector, and inspected the wiring. Didn't make any difference, the car still runs (barely) like s^&*.

Colorado964turbo

Is it cutting out while it is running?

I had issues with my TCU clicking at certain RPM's. I did some reasearch and couldn't find out much about the unit. To make matters worse my car is twin plugged, without a distributor.

wrhopcraft

Starts and idles fine. Coughs, sputters, and backfires as you try to open the throttle. Sometimes it just dies.

John McM

For what it's worth, I've been inside the box. You might have the same problem, a defunct relay https://rennlist.com/forums/964-turb...ml#post6129847

wrhopcraft

John - Your excellent posts were actually the ones that got me looking at the TCU in the first place. Can you tell me how to test the two relays on the board? Blowing up the board with a bad testing procedure would really make for a bad day!

John McM

Relays are very simple. A circuit is switched by energising a coil that moves an arm and closes the circuit. In this application there are only two things that can go wrong [assuming the relay is the defective part] 1. the coil isn't working because it has bad connections or a broken wire, or 2. the coil works but the contacts don't close due to a weakened coil or problems with the contacts.

In my case the coil wasn't working. I tested it by using a 9 -volt radio battery across the coil wires and nothing happened. Wiring in a new relay fixed the problem. Unfortunately that is as much help as I can give right now. My car is in another country and I don't have access to wiring diagrams. Good luck.