P0585

P0585-SPEED CONTROL SWITCH 1 - 2 CORRELATION

For a complete wiring diagram Consult Diagrams/Electrical

- When Monitored:
With the ignition on and battery voltage greater than 10.4 volts.

- Set Condition:
The PCM detects that the (V37) S/C Signal 1 and the (V38) S/C Signal 2 input voltages do not match.

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.Initial Inspection and Diagnostic Overview

Diagnostic Test

1. DTC IS ACTIVE

NOTE: This DTC is a two trip fault. If the scan tool indicates a one trip failure, the possible cause may have been the customer pressing both switches simultaneously. Test drive the vehicle and activate the Speed Control system. If the DTC matures to an active fault a repair is necessary.

Start the engine and allow it to idle for at least 60 seconds.

WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death.

NOTE: It may be necessary to test drive the vehicle and operate the speed control in order for this DTC to set.

With a scan tool, select View DTCs.
Is the status Active for this DTC?

Yes

- Go to2

No

- Refer to the *CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure.Checking For An Intermittent DTC

2. LEFT SPEED CONTROL SWITCH

Turn the ignition off.
Disconnect the Left Speed Control Switch harness connector.
Turn the ignition on.
With the scan tool, read the (V37) S/C Signal 1 and (V38) S/C Signal 2 input voltages.

NOTE: The switch voltages should be approximately 5.0 volts (plus or minus.1 volt) with the connector disconnected.

Turn the ignition off.
Connect a jumper wire between the (V37) S/C Signal 1 and the (K975) S/C Switch Ground circuit in the Left Speed Control Switch harness connector.
Turn the ignition on.
With the scan tool, read the (V37) S/C Signal 1 input voltage.

NOTE: The switch voltage should be approximately 0.0 volts (plus or minus.1 volt) with the jumper wire in place.

Turn the ignition off.
Connect a jumper wire between the (V38) S/C Signal 2 and the (K975) S/C Switch Ground circuit in the Left Speed Control Switch harness connector.
Turn the ignition on.
With the scan tool, read the (V38) S/C Signal 2 input voltage.

NOTE: The switch voltage should be approximately 0.0 volts (plus or minus.1 volt) with the jumper wire in place.

Is the voltage on the scan tool displayed as described above?

Yes

- Replace the Left Speed Control Switch.
- Perform the PCM Verification Test.Powertrain Verification Test

No

- Go to3

3. RIGHT SPEED CONTROL SWITCH

Turn the ignition off.
Disconnect the Right Speed Control Switch harness connector.
Turn the ignition on.
With the scan tool, read the (V37) S/C Signal 1 and (V38) S/C Signal 2 input voltages.

NOTE: The switch voltages should be approximately 5.0 volts (plus or minus.1 volt) with the connector disconnected.

Turn the ignition off.
Connect a jumper wire between the (V37) S/C Signal 1 and the (K975) S/C Switch Ground circuit in the Right Speed Control Switch harness connector.
Turn the ignition on.
With the scan tool, read the (V37) S/C Signal 1 input voltage.

NOTE: The switch voltage should be approximately 0.0 volts (plus or minus.1 volt) with the jumper wire in place.

Turn the ignition off.
Connect a jumper wire between the (V38) S/C Signal 2 and the (K975) S/C Switch Ground circuit in the Right Speed Control Switch harness connector.
Turn the ignition on.
With the scan tool, read the (V38) S/C Signal 2 input voltage.

NOTE: The switch voltage should be approximately 0.0 volts (plus or minus.1 volt) with the jumper wire in place.

Is the voltage on the scan tool displayed as described above?

Yes

- Replace the Right Speed Control Switch.
- Perform the PCM Verification Test.Powertrain Verification Test

No

- Go to4

4. SPEED CONTROL SIGNAL CIRCUIT SHORTED TO VOLTAGE

Turn the ignition off.
Disconnect the Powertrain Control Module (PCM) connector.
Turn the ignition on.
Measure the voltage of the (V37) S/C Signal 1 circuit.
Measure the voltage of the (V38) S/C Signal 2 circuit.
Is there any voltage present on either circuit?

Yes

- Repair the circuit for a short to voltage.
- Perform the PCM Verification Test.Powertrain Verification Test

No

- Go to 5

5. SPEED CONTROL SIGNAL CIRCUIT SHORTED TO GROUND

Turn the ignition off.
Measure the resistance between ground and the (V37) S/C Signal 1 circuit.
Measure the resistance between ground and the (V37) S/C Signal 1 circuit.
Is the resistance above 100 ohms for both circuits?

Yes

- Go to 6

No

- Repair the circuit for a short to ground.
- Perform the PCM Verification Test.Powertrain Verification Test

6. SPEED CONTROL SIGNAL CIRCUIT SHORTED TO THE (K975) S/C SWITCH GROUND CIRCUIT

Measure the resistance between the (V37) S/C Signal 1 circuit and the (K975) S/C Switch Ground circuit.
Measure the resistance between the (V38) S/C Signal 2 circuit and the (K975) S/C Switch Ground circuit.
Is the resistance above 100 ohms for both circuits?

Yes

- Go to 7

No

- Repair the circuit for a short to the (K975) S/C Switch Ground circuit.
- Perform the PCM Verification Test.Powertrain Verification Test

7. (V37) S/C SIGNAL 1 CIRCUIT OPEN OR HIGH RESISTANCE

CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals, resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis.

Measure the resistance of the (K975) S/C Switch Ground circuit between the Left Speed Control Switch harness connector and the appropriate terminal of special tool #8815 and between the Right Speed Control Switch harness connector and the appropriate terminal of special tool #8815.
Is the resistance below 5.0 ohms?

Yes

- Go to10

No

- Repair the (K975) S/C Switch Ground circuit for an open circuit or high resistance.
- Perform the PCM Verification Test.Powertrain Verification Test

10. POWERTRAIN CONTROL MODULE (PCM)
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Left Speed Control Switch and the Powertrain Control Module (PCM) and between the Right Speed Control Switch and the Powertrain Control Module (PCM).
Look for any chafed, pierced, pinched, or partially broken wires.
Look for broken, bent, pushed out or corroded terminals.
Search for any Technical Service Bulletins that may apply.
Were any problems found?

Yes

- Repair as necessary.
- Perform the PCM Verification Test.Powertrain Verification Test

No

- Replace the Powertrain Control Module (PCM).
- Perform the PCM Verification Test.Powertrain Verification Test