Changing over to a distributor with the classic FAST box Cam Sync issue


Active Member
Dec 9, 2004
The Cam Sync value on my classic FAST dashboard reads 0 when the engine is running.

I am using an old classic FAST harness adapter (not caspers) and it does not have a wire going to D3 on the FAST box. D3 is the Cam Rtn according to the ECU pinout. I do see a wire going into C3 which is the Cam+ input as labeled on the ECU pinout. So I am guessing this C3 (Cam+) doubles as the discrete input that is connected to the cam position sensor. Actually, the cam position sensor goes through the CCCI module first then to the ECU.

So I think I am not getting a reference from the distributor. But how did the discrete signal work without the CAM RTN wire installed. Surely it is getting a ground ref from somewhere.

I appreciate any help
Also, I have the caspers CCCI pass through module installed. Interestingly, the cam position sensor and the crank sensor do not have a dedicated ground return. They used the CCCI ground return for a common return.

I wonder if I need to run a separate shielded twisted pair from the dizzy outputs to the FAST cam inputs??????
I wonder if the pass through caspers electronics module will connect the negative side of the distributor output with the ground reference of the crank sensor?
Well I found and followed the ground wire coming from the cam position sensor. It goes into the classic FAST box as DISTRTN pin J2. The Crank sensor goes into the FAST box as CRKREF pin J3. So I disconnected the DISTRTN wire and rerouted it to D3 which is the CAM RTN. STILL no Cam sync :(. Looking for other options
I measured AC voltage coming from the distributor across the CAM+ and CAM- at the FAST connectors. So I have verified the signal is getting to the FAST. But still no cam sync on my dashboard. I tried to ground the DISTRTN instead of leaving it floating, but this yielded no cam sync. I am scratching my head.
So since the FAST originally used the DISTRTN for the ground return of the Cam position sensor. I am going to return the negative wire of the distributor to it. Then I am going to ground CAM RTN to chassis ground and see what happens