How do I enter the Diagnostic Mode and access Coe P030 and clear the codes if I need to?

RAY WALTERS

MEMBER
1994 CADILLAC DEVILLE CONCOURS
66,000 MILES

1994 Cad Deville Concourse 4.6L Northstar V8 engine.
Engine idles up and down on it's own. Code P030 comes up. Installed a new ISC (Idle Speed Control motor). Throttle Position sensor code came up and will replace it tomorrow. On the big machine it reads.4V and it should be higher. I have all 3 big books 1, 2, and 3 Service Manuals and have not found that information on "how to".

Regards,
Ray

1 Reply

FACTORYJACK

MECHANIC
4,159 POSTS

On how to enter diagnostics? On a 94 it is off and warmer pushed and held with the key on, until the displays light, it will then go through codes of all modules(if there is any). After all modules have reported, it will read PCM, on the info center. From there, pushing fan up will select the module, and then fan down will cycle through all executables for said module(PCM, ACM, ABS, etc.). You will find the option to clear codes there. I don't have any older manuals at my disposal at this time, but you should be able to find the on-board diagnostics process laid out in the manual you have. Look under topics like powertrain control module, computers and control systems, that type of stuff. It should not be in 4.6, or 4.9 specifically, but it might be. The operation is the same, so it should be in a more general sub-section. If you reply tonight, I may not get back. If I see a reply tomorrow, I will look in a manual, and offer you page numbers, or section heading to further assist.