2010 Cadillac CTS Sedan AWD V6-3.6L Page 1010
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (See: Diagnostic Trouble Code Descriptions/Powertrain Diagnostic Trouble Code
(DTC) Type Definitions)
Scan Tool Reference
Control Module References (See: Testing and Inspection/Programming and Relearning) for scan tool information
Special Tools
* J 23738-A - Mityvac
* J 35555 - Metal Mityvac
* For equivalent regional tools, refer to Special Tools (See: Powertrain Management/Computers and Control Systems/Tools and Equipment).
Circuit/System Verification
1. Verify that DTC P0641, P0651, or P0697 is not set.
瀚慖f any of the DTCs are set refer to DTC P0641, P0651, P0697, or P06A3 (ECM, LF1) (See: P Code Charts/P0641).
2. Ignition ON, observe the scan tool MAP Sensor parameter. The reading should be between 0.20-4.80 V.
3. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the
conditions that you observed from the Freeze Frame/Failure Records data.
Circuit/System Testing
1. Ignition OFF for 90 s, disconnect the harness connector at the B74 MAP sensor.
2. Test for less than 5 ohm between the low reference circuit terminal 2 and ground.
瀚慖f greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the K20
ECM.
3. Ignition ON, test for 4.8-5.2 V between the 5 V reference circuit terminal 1 and ground.
瀚慖f less than the specified range, test the 5 V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal,
replace the K20 ECM.
瀚慖f greater than the specified range, test the 5 V reference circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.
4. Verify the scan tool MAP Sensor parameter is less than 1 kPa (0.2 psi).
瀚慖f greater than the specified range, test the signal circuit terminal 3 for a short to voltage. If the circuit tests normal, replace the K20 ECM.
5. Install a 3 A fused jumper wire between the signal circuit terminal 3 and the 5 V reference circuit terminal 1. Verify the scan tool MAP
Sensor parameter is greater than 127 kPa (18.4 psi).
瀚慖f less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace
the K20 ECM.
6. If the circuits test normal, test or replace the B74 MAP sensor.
Component Testing
Note: You must perform the Circuit/System Testing in order to verify the integrity of the MAP sensor circuits before proceeding with the
Component Testing.
Erratic Signal Test
1. Ignition OFF, remove the B74 MAP sensor.
2. Install a 3 A fused jumper wire between the 5 V reference circuit terminal 1 and the corresponding terminal of the B74 MAP sensor.
3. Install a jumper wire between the low reference circuit terminal 2 of the B74 MAP sensor and ground.
4. Install a jumper wire at terminal 3 of the B74 MAP sensor.
5. Connect a DMM between the jumper wire from terminal 3 of the B74 MAP sensor and ground.
6. Ignition ON, with the J 23738-A - Mityvac or the J 35555 - Metal Mityvac , slowly apply vacuum to the sensor while observing the voltage
on the DMM. The voltage should vary between 0-5 V without any spikes or dropouts.
瀚慖f the voltage reading is erratic, replace the B74 MAP sensor.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
