Page 1297 of 5267

3.(B22) VEHICLE SPEED SENSOR SIGNAL CIRCUIT OPEN BETWEEN CAB AND PCM
Turn the ignition off.
Measure the resistance of the (B22) Vehicle Speed Signal circuit
between the PCM harness connector and the CAB Module harness
connector.
Is the resistance above 5.0 ohms?
Ye s>>
Repair the open in the (B22) Vehicle Speed Signal circuit
between the CAB and PCM.
Perform POWERTRAIN VERIFICATION TEST. (Refer to 9 -
ENGINE - STANDARD PROCEDURE)
No>>
Go To 4
4.(B22) VEHICLE SPEED SENSOR SIGNAL CIRCUIT SHORT TO GROUND
Measure the resistance between ground and the (B22) Vehicle Speed
Signal circuit at the PCM harness connector.
Istheresistancebelow100ohms?
Ye s>>
Repair the short to ground in the (B22) Vehicle Speed Sig-
nal circuit between the CAB and PCM.
Perform POWERTRAIN VERIFICATION TEST. (Refer to 9 -
ENGINE - STANDARD PROCEDURE)
No>>
Go To 5
5.PCM
NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal
push out. Repair as necessary.
Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and
Ground circuits.
If there are no possible causes remaining, view repair.
Repair
Replace and program the Powertrain Control Module per Service Information.
Perform POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
Page 1298 of 5267
P0505-IDLE AIR CONTROL MOTOR CIRCUITS
For a complete wiring diagramRefer to Section 8W.
Page 1299 of 5267

When Monitored:
At power-up and battery voltage greater than 11.5 volts.
Set Condition:
The PCM senses a short to ground or battery voltage on any of the four Idle AirControl (IAC) driver circuits
for 100 ms while the IAC motor is active.
Possible Causes
(K40) IAC #1 DRIVER CIRCUIT SHORTED TO (K60) #2, (K39) #3, OR (K59) #4 IAC DRIVER CIRCUITS
(K60) IAC #2 DRIVER CIRCUIT SHORTED TO (K39) IAC #3 OR (K59) IAC #4
(K39) IAC #3 DRIVER CIRCUIT SHORTED TO (K59) IAC #4 DRIVER CIRCUIT
IAC DRIVER CIRCUIT SHORTED TO VOLTAGE
IAC DRIVER CIRCUIT SHORTED TO GROUND
IAC MOTOR
PCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)
1.GOOD TRIP EQUAL TO ZERO
Ignition on, engine not running.
With the scan tool, read DTCs and record the related Freeze Frame data.
Is the Good Trip Counter displayed and equal to zero?
Ye s>>
Go To 2
No>>
Refer to the INTERMITTENT CONDITIONSymptom (Diagnostic Procedure).
Perform POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
2.IAC #1 DRIVER CIRCUIT SHORTED TO #2, #3, OR #4
Turn the ignition off.
Disconnect the IAC Motor harness connector.
Disconnect the C1 PCM harness connector.
NOTE: The following steps are checking for a short between the
IAC Driver circuits.
Measure the resistance between the (K40) IAC #1 Driver circuit and #2,
#3, #4 Driver circuits.
Istheresistancebelow100ohmsonanyoftheDrivers?
Ye s>>
Repair the short between the IAC Driver circuits.
Perform POWERTRAIN VERIFICATION TEST. (Refer to 9 -
ENGINE - STANDARD PROCEDURE)
No>>
Go To 3
Page 1300 of 5267
3.(K60) IAC #2 DRIVER CIRCUIT SHORTED TO (K39) IAC #3 OR (K59) IAC #4 DRIVER CIRCUITS
NOTE: The following steps are checking for a short between the
IAC Driver circuits.
Measure the resistance between the (K60) IAC #2 Driver circuit and
(K39) IAC #3, (K59) IAC #4 Driver circuits.
Istheresistancebelow100ohmsonanyoftheDrivers?
Ye s>>
Repair the shorted between the IAC Driver circuits.
Perform POWERTRAIN VERIFICATION TEST. (Refer to 9 -
ENGINE - STANDARD PROCEDURE)
No>>
Go To 4
4.(K39) IAC #3 DRIVER CIRCUIT SHORTED TO THE (K59) IAC #4 DRIVER CIRCUIT
NOTE: The following steps are checking for a short between the
Driver Circuits.
Measure the resistance between the (K39) IAC #3 Driver circuit and the
(K59) IAC #4 Driver circuit.
Istheresistancebelow100ohms?
Ye s>>
Repair the short between the IAC Driver circuits.
Perform POWERTRAIN VERIFICATION TEST. (Refer to 9 -
ENGINE - STANDARD PROCEDURE)
No>>
Go To 5
Page 1301 of 5267

5.IAC DRIVER CIRCUITS SHORTED TO VOLTAGE
Remove the ASD Relay.
Using a jumper wire, jumper between the (A14) Fused B+ circuit and
(K342) ASD Relay Output circuit in the PDC.
Ignition on, engine not running with the PCM and IAC harness connec-
tors disconnected.
Measure the voltage on each of the IAC Driver circuits.
Is the voltage above 1.0 volt at any IAC Driver circuit?
Ye s>>
Repair the short to voltage onthe appropriate IAC Driver
circuit.
Perform POWERTRAIN VERIFICATION TEST. (Refer to 9 -
ENGINE - STANDARD PROCEDURE)
No>>
Go To 6
NOTE: Remove the jumper wire and install the ASD Relay before
continuing.
6.IAC DRIVER CIRCUITS SHORTED TO GROUND
Turn the ignition off.
Repeat each measurement for each IAC Driver circuit.
Measure the resistance between ground and each IAC Driver circuit.
Is the resistance below 100 ohms at any IAC Driver circuit?
Ye s>>
Repair the short to ground in the appropriate IAC Driver cir-
cuit.
Perform POWERTRAIN VERIFICATION TEST. (Refer to 9 -
ENGINE - STANDARD PROCEDURE)
No>>
Go To 7
Page 1302 of 5267
7.IAC MOTOR OPERATION
Turn the ignition off.
Connect the C1 PCM harness connectors.
Start and idle the engine.
Using a test light connected to ground, probe the IAC Driver #1 circuit
for 10 seconds.
Repeat the above test for the remaining IAC Motor Driver circuits.
Does the test light turn on and off while probing each IAC
MotorDrivercircuits?
Ye s>>
Replace the Idle Air Control Motor.
Perform POWERTRAIN VERIFICATION TEST. (Refer to 9 -
ENGINE - STANDARD PROCEDURE)
No>>
Replace and program the Powertrain Control Module per
Service Information.
Perform POWERTRAIN VERIFICATION TEST. (Refer to 9 -
ENGINE - STANDARD PROCEDURE)
Page 1303 of 5267

P0513-INVALID SKREEM KEY
For a complete wiring diagramRefer to Section 8W.
When Monitored:
Ignition on.
Set Condition:
The Gateway detects that the Secret Key message is invalid or missing. One Trip Fault.
Possible Causes
WCM/SKREEM
POWERTRAIN CONTROL MODULE
GATEWAY MODULE
COMMUNICATION PROBLEM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING).
Diagnostic Test
1.ACTIVE DTC
Ignition on, engine not running.
With the scan tool, read the Gateway Module DTCs.
Is the DTC active at this time?
Ye s>>
Go To 2
No>>
Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
2.COMMUNICATION (CAN BUS or J1850)
NOTE: For vehicle communication problems, use the scan tool to refer to theNetwork Review Screen. The
screen depicts a high level view of the vehicle network. Fault and problem areas appear in red. Selecting
any of the network components allows access to the source of the problem.
Does the scan tool display a Vehicle Network problem or NO RESPONSE condition?
Ye s>>
Refer to the appropriate BUS Communication test in the Section 8 ELECTRONIC CONTROL MODULE
- ELECTRICAL DIAGNOSTICS.
No>>
Go To 3
3.SKREEM/SKIM TROUBLE CODES SET
With the scan tool, check for SKREEM/SKIM DTCs.
Are any DTCs present in the SKREEM/SKIM?
Ye s>>
Refer to Section 8 - Electrical VEHICLE THEFT SECURITY - ELECTRICAL DIAGNOSTICS and perform
the appropriate Diagnostic Procedure.
No>>
Go To 4
Page 1304 of 5267
4.GATEWAY MODULE
Turn the ignition off.
Replace and program the Gateway Module in accordance with Service Information.
Ignition on, engine not running.
With the scan tool, erase all SKREEM and PCM DTCs.
Attempt to start and idle the engine.
With the scan tool, read the Gateway Module DTCs.
Does the scan tool display this code?
Ye s>>
NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or termi-
nal push out. Repair as necessary. Replace and program the Powertrain Control Module per Service
Information.
Perform SKREEM VERIFICATION. (Refer to 8 - ELECTRICAL/VEHICLE THEFT SECURITY - STAN-
DARD PROCEDURE)
No>>
Te s t C o m p l e t e .