Does an 1985 corolla gt-s have a service plug on the firewall?

If you mean diagnostics port? No.

You jump the check engine light connector, and then watch the CEL blink inside. There are only ten codes for it.

Red wrote:If you mean diagnostics port? No.

You jump the check engine light connector, and then watch the CEL blink inside. There are only ten codes for it.

Thank you, I've had 86 and 87's and I've been going nuts looking for it. Could you lead me to the check engine light connector please, also with out the diagnostic port how do I set my timing properly?

Offhand, the CEL jumper is one of the two yellow? green? plastic plugs that used to have rubber caps on them, hanging on the firewall, passenger side. Fastest to find with a picture, or the diagram in the shop manuals.

You set your timing the way real men have always set their timing. By putting in a jumper to disable the vacuum advance (I forget if that's the same jumper or the one next to it) and then you hook up a timing light. You will need to remove the "snorkel" on the air intake in order to get an eyeball down on the timing mark as well.

With any luck someone with a better memory will post the fine points on that before I can get back with them.<G>

Red wrote:Offhand, the CEL jumper is one of the two yellow? green? plastic plugs that used to have rubber caps on them, hanging on the firewall, passenger side. Fastest to find with a picture, or the diagram in the shop manuals.

You set your timing the way real men have always set their timing. By putting in a jumper to disable the vacuum advance (I forget if that's the same jumper or the one next to it) and then you hook up a timing light. You will need to remove the "snorkel" on the air intake in order to get an eyeball down on the timing mark as well.

With any luck someone with a better memory will post the fine points on that before I can get back with them.<G>

Thank you I found the plug it was yellow. I also discovered I have code 6 so the hunt for repair continues.

Code 6 is the "RPM signal". It means no signal was received on the G or NE lines, which are redundant coils on the distributor that tell the ECU that the distributor is turning, and presumably the engine is running. Look for the pack connector coming off the distributor, if you are lucky it is just loose.

Red wrote:Code 6 is the "RPM signal". It means no signal was received on the G or NE lines, which are redundant coils on the distributor that tell the ECU that the distributor is turning, and presumably the engine is running. Look for the pack connector coming off the distributor, if you are lucky it is just loose.

awesome, thank you for the info.