Pinpoint Tests

The following tests give detailed information on component fault diagnosis.

1. Power supply
a. Check fuse F10 in LH 'A' post base fuse-box is intact.
b. Unplug harness connector from SCCM and check for battery supply voltage to ground, at pins 1 and 2 with ignition on. If supply is not recorded on either pin switch off ignition and check harness wiring continuity from LH 'A' post base fuse-box to splice FCS16.
c. If supply is recorded at pin 1 only check brake and clutch (where installed) switch contacts (closed when pedals not operated). For vehicles with automatic transmission ensure clutch pedal switch link is correctly installed. Examine harness wiring and check continuity between pin 2 and splice FCS16.
d. If supply is recorded at pin 2 only examine harness wiring and check continuity from pin 1 to splice FCS16.

Speed Control Power Supply:

1. Speed Control Control Module (SCCM)
2. Clutch Switch/Link
3. Brake Switch
4. LH 'A' Post Base Fuse-box
5. Switch Pack
6. Column Switch gear Dimmer
7. Dump Valve
8. Control Valve/Pump Unit
9. Gear Position Module
10. ABS Control Module
11. Instrument Pack

2. Switch pack assembly
a. Unplug switch pack connector and check for battery voltage between pin 4 and ground with ignition off. If battery voltage is not present, switch ignition off and examine wiring harness, checking continuity between pin 4 and splice FCS16.
b. Test operation of switches between pins as follows:

ON: Normally open; closes on operation completing circuit between pins 4 and 5 and pins 1 and 5. A resistance of less than 1 Ohm should be recorded when testing pins 4 and 5. Minimal resistance should be recorded when testing pins 1 and 5.

SET: Normally open; closes on operation completing circuit between pins 2 and 5. A resistance of approximately 100 Ohm should be recorded.

RES: Normally open; closes on operation completing circuit between pins 2 and 5. A resistance of approximately 330 Ohm should be recorded.

c. Examine wiring harness and check continuity between pin 5 and ground.

Speed Control Switches, Fig.1:

1. Speed Control Control Module (SCCM)
2. Clutch Switch/Link
3. Brake Switch
4. LH 'A' Post Base Fuse box
5. Switch Pack
6. Column Switch gear Dimmer
7. Dump Valve
8. Control Valve/Pump Unit
9. Gear Position Module
10. ABS Control Module
11. Instrument Pack

3. Brake switches
a. Unplug switch connector and chock for battery voltage between pin 3 and ground with ignition on. If battery voltage is not present switch off ignition and examine harness, checking continuity between pin 3 and splice FCS16.
b. Test switch continuity across pins as follows:

Pin 3 - Pin 2; normally closed, opens on pedal operation breaking circuit continuity. Also, check continuity from pin 2 to clutch switch (where installed) or link pin 1.

Pin 1 - Pin 4; normally open, closes on pedal operation completing circuit continuity. Also, check continuity from switch pin 1 to SCCM pin 15 and switch pin 4 to ground.

4. Clutch switch (where installed) or link
a. Unplug switch connector and check for battery voltage between pin 1 and ground with ignition on. If battery voltage is not present switch off ignition and examine harness, checking continuity between pin 1 and splice FCS16.
b. Check continuity across switch pins 1 and 2, switch (where installed) is normally closed and opens on pedal operation.
c. Examine wiring harness, checking continuity between pin 2 and SCCM pin 12.

Brake And Clutch Switches, Fig.1:

1. Speed Control Control Module (SCCM)
2. Clutch Switch/Link
3. Brake Switch
4. LH 'A' Post Base Fuse-box
5. Switch Pack
6. Column Switchgear Dimmer
7. Dump Valve
8. Control Valve/Pump Unit
9. Gear Position Module
10. ABS Control Module
11. Instrument Pack

5. Dump valve
a. Unplug connector from valve and test continuity across solenoid (pins 1 and 2). A resistance value of approximately 40 Ohm should be recorded.
b. Examine harness wiring, checking continuity between valve pins 1 and 2 and SCCM pins 4 and 3 respectively.

6. Control valve/pump unit
a. Unplug connector from unit and test continuity across valve solenoid (pins 3 and 2). A resistance value of approximately 85 Ohm, should be recorded.
b. Test continuity across pump motor (pins 3 and 1, refer to image). A resistance value of approx. 20 Ohm should be recorded.
c. Examine harness wiring, checking continuity between unit pins 1, 2 and 3 and SCCM pins 20, 10 and 3 respectively.

Dump Valve And Control Valve/Pump Unit, Fig.1:

1. Speed Control Control Module (SCCM)
2. Clutch Switch/Link
3. Brake Switch
4. LH 'A' Post Base Fuse-box
5. Switch Pack
6. Column Switchgear Dimmer
7. Dump Valve
8. Control Valve/Pump Unit
9. Gear Position Module
10. ABS Control Module
11. Instrument Pack

7. Gear position input
a. Examine harness wiring, checking continuity between SCCM pin 18 and transmission decoder module (6 cylinder) or linear switch (12 cylinder)
b. Examine transmission fault diagnosis.

8. Road speed input
a. Examine harness wiring, checking continuity between SCCM pin 6 and instrument pack.
b. Examine instrument pack fault diagnosis.

9. Traction control input
a. Examine harness wiring, checking continuity between SCCM pin 9 and ABS TC/CM.
b. Examine ABS TC/CM fault diagnosis.

Pinpoint Tests

Speed Control Power Supply:

Speed Control Switches, Fig.1:

Brake And Clutch Switches, Fig.1:

Dump Valve And Control Valve/Pump Unit, Fig.1:

Gear Position, Road Speed And Traction Control Inputs, Fig.1: