The coil pack is general mounted down on/inside the intake manifold. It is commonly relocated elsewhere to gain better access to it or when using an aftermarket, sheet metal intake manifold. The coil pack provides spark through the plug wires and then spark is generated at the spark plugs themselves.
Our DSM coil packs consist of two coils. Cylinders 1 & 4 are in one coil and cylinders 2 & 3 are in another. Each coil sends spark to the dedicated two cylinders at a time. For example, when spark is sent to cylinder 1, it is simultaneously sent to cylinder 4.
WIRING
The 1990 coil pack has four pins compared to three pins for the 1991+, the 1990 has an external tach gate on the coil pack for the tachometer circuit and that fourth wire runs to the noise filter, connector B-00 in the FSM.
1990 Coil Pack
1=Yellow/Black Power Transistor Collector Coil B (2&3)
2=Yellow/Green Power Transistor Collector Coil A (1&4)
3=White Tachometer Gate output (to noise filter and ECU)
4=Black/White +12v IG1
1991-1994 Coil Pack
1=Yellow/Black Power Transistor Collector Coil B (2&3)
2=Yellow/Green Power Transistor Collector Coil A (1&4)
3=
4=Black/White +12v IG1
1990 Power Transistor Module
1=Yellow/Green Collector 1 (OC1) Coil A
2=Yellow Base 1 (IB1) ECU pin 54
3=Black Ground
4=NC
5=Yellow/Red Base 2 (IB2) ECU pin 55
6=Yellow/Black Collector 2 (OC2) Coil B
1991+ Power Transistor Module
1=Yellow/Black Collector 1 (OC1) Coil B
2=Yellow/Red Base 1 (IB1) ECU pin 55
3=Black Ground
4=NC
5=White Tach Gate output ECU pin 109 and Gauge Cluster
6=Black/White +12 IG1
7=Yellow Base 2 (IB2) ECU pin 54
8=Yellow/Green Collector 2 (OC2) Coil A
You’ll note that the wire colors match but they switched which of the two transistors was used in the PTM.
The 1990 gauge cluster is driven from the output of the noise filter. You need to retain it unless you swap to the later cluster. It should be bolted to the intake manifold somewhere.
The 1991+ ECU should now get it’s tachometer signal from pin 5 of the 91+ PTM.
