Faulty ignition module?

Can anyone tell me if the ignition module is faulty if it flags a red light while being tested that says it is in bypass? I took my to the parts store to have it tested and they said it is in bypass. Does that mean that the electronic spark control is not timing the truck and the computer is. Or vice a versa?

Can anyone tell me if the ignition module is faulty if it flags a red light while being tested that says it is in bypass? I took my to the parts store to have it tested and they said it is in bypass. Does that mean that the electronic spark control is not timing the truck and the computer is. Or vice a versa?

SWOOP: Can't promise any help with your problem, but in order for us to try to help you, give us the year, model and engine???

Sorry, I own an 89 chevy sub. 5.7L ...I have had a issue with the timming being erratic. So after a full tune up...cap,rotor, plugs and wires, and fuel filter..I had the ignition control module checked out at the parts store and it turned out to be bad. They said it is in bypass. They were not sure what it meant, but the scanner they plugged it into checked for low rpm, high rpm, a couple of other things along with a bypass. Just wondering if anyone had insight on this. Thank you

OK Swoop: I got out my OLD '88 manual (I keep them all) and there is a bypass circuit. The circuit # is 424 and the wire is Tan/Black going to the Dist. There is a connector in that wire somewhere between the dist and firewall. I seem to remember on my '85 Blazer that I had to disconnect that wire for the base timing set, but the '88 manual does not mention that. It does say to read and follow the emmisions decal in the engine compt for the timing procedure.

The bypass circuit is controlled by the ECM, but I can't find what the input is to the ECM that controls it. Wish I could be more help...............Steve