The Volvo 740 Turbo APC Project, APC Wiring

Wiring Diagram For APC System:

APC Wiring diagram. Components:
148:Power from +/15 terminal on ignition coil.
22: Fuse (10 amp)
147: Ignition Coil Terminal -/1.
178: Knock Sensor.
179: Solenoid Valve.
180: Pressure Transmitter
123: Ground for solenoid and control unit.

Wiring the APC is simple. Only 9 pins are necessary.

The numbers for the pins can be seen on the back side of the control unit plug once the top cover is removed. There will be several wires not used for this installation, they can be removed. I will soon have a picture of the plug itself and how to remove the individual connectors.

Pin 13 is a fused power feed from the ignition. (I took the power from the +/15 connection of the coil and installed an in line fuse close to the coil)**

Pin 10 goes to the larger of the two spade connectors on the pressure transmitter.

Pin 23 goes to the smaller of the two spade connectors on the pressure transmitter.

Pin 12 is the signal to the solenoid valve. (I grounded the solenoid on the inner fender)

Pin 4 is the shielded ground for the knock sensor

Pin 16 goes to the GREEN wire of the knock sensor lead.

Pin 17 goes to the BROWN wire in the knock sensor lead.

Pin 5 is a ground for the control unit. (I grounded this at the same spot as the solenoid)

Pin 25 is for an engine RPM signal. (I took this from the -/1 connection on the coil)

Wire Conectors:

The wire connectors for the ECM are available from Saab (Part Number: 91 20 957). You will need at least 9 of them, I would recommend getting a few spares just in case you mess one up. They require a special crimping tool available from most tool dealers. Be sure to crimp them properly or you will get a bad connection!!

connector.jpg (5227 bytes)
91 20 957

Good Crimp! YES!

Bad Crimp! NO!

Below in a picture of the crimping tool you will need to get for the factory wire connectors. The ones shown are Mac brand, however Snap-On and most other professional tool companies make the same thing.

crimper.jpg (6714 bytes)

**Special Notes:

If you're installing APC on a car with a ballast resistor, do not take the power from the coil + terminal. Instead, find a suitable +12v power supply that is switched on and off with the ignition.

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