ECM Terminals

The following information is a listing of the 56 terminal locations (one 24 pin terminal, and one 32 pin terminal) in the two plastic connectors which attach the main wiring loom to the ECM. A graphic representation of these connectors appears in illustrations on pages - of Part 9, in conjunction with an identification chart, and with locations keyed in the same alpha-numeric manner (ie A-1, B-2, C-3, D-4 etc.) as in the following Tables.

Each connection will be indicated by its alpha-numeric position (physical location in the ECM terminal connector). Each connection will also have information relative to the color code(s) of the wire used in that terminal and the appropriate GM Circuit number(s) and name(s), and the primary and, in some cases, the secondary connection point(s) plus information about related wiring (ie., in the case of a circuit where the ECM provides a ground, we will also explain where the power source for that component originates, etc.). Also, we will indicate if the circuit in question can be deleted and, when removed, what type of connections should be made to keep that particular circuit from creating problems with other circuits, or setting false trouble codes by its removal. By referring to schematic diagrams, to on pages to , in Part 10 of this book, while reading through the ECM terminal section, you will be able to gain an overall understanding of the TPI wiring system and how to adapt it to your individual requirements.

You may, occasionally, find different colour wires in the individual ECM terminal connections than the ones listed here. While colour codes are important in tracing different wires in a wiring loom, the point must be made here, that even more important than the colour codes are the circuit numbers and their proper connection points. Simply stated, if the circuit in question has the proper termination points, the colour codes are merely a helpful convenience. We strongly suggest that all circuits be doublechecked with a continuity tester to make absolutely sure each individual circuit is properly connected.

Be very careful when wiring the relays.

While the actual circuits involved are the same, the relay terminal positions, as indicated by the letters, A, B, C, etc are different, due to the use of different style relays and connectors on different year vehicles, in what we shall refer to as Design 1 and Design 2 relays.

88 and 89 Camaro and Firebird systems use Design 2 relays for the MAF power and MAF burn-off relays, and a Design 1 relay for the fuel pump application.

Where necessary, a terminal listing for both the Design 1 and Design 2 styles is described. The differences are reflected in the wiring diagrams and by the illustration of the obvious physical differences in appearance between the connector types, as shown in on page . There is also information relating to year and model applications, and the appropriate part numbers, of the 1st and Design 2 relays in table . on page .

Remove the ECM from the wiring loom connectors before doing any circuit testing or modifications, and be sure to solder all connections!

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