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Questions and Answers

Accessing Geo DTCs

Q. I have a 1994 (8/93) Geo Metro, 3 cylinder, automatic with TBI.

I am trying to set the timing and my Haynes manual says to put a jumper wire between the C & D terminals of the diagnostic connector. The Haynes manual shows a connector with only 4 sockets.

The diagnostic connector on my car has six sockets (5 used). The wires are black, purple/green, purple/red, purple/yellow and purple.

Is this the right connector and if so which terminals should I jump?

A. Diagnostic Trouble Codes (DTCs) are stored in ECM memory and can be read through a Diagnostic Scan Tool plugged into the DLC or by counting the flashes of the Malfunction Indicator Lamp (MIL) after grounding the DIAG SW connector or by counting the flashes of a test light after grounding the diagnostic request terminal in the duty check DLC. When either terminal is grounded, the ECM enters its diagnostic mode and outputs DTCs to either the MIL or, if a test light is used, to the diagnostic output terminal of the duty check DLC.

Data Link Connector And Junction Block

Duty Check DLC

Additional Information provided courtesy of ALLDATA

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