2010 Cadillac CTS Sedan AWD V6-3.0L Page 1775
1. Ignition ON, observe the scan tool Ignition 1 Signal and the EC Ignition Relay Feedback parameters to determine which is more than 3 V
lower than the other.
Note: The Ignition 1 Signal is supplied by the ignition 1 relay. The EC Ignition Relay Feedback signal is supplied by the powertrain relay.
2. Ignition OFF, remove the relay that corresponds to the scan tool parameter that is more than 3 V lower.
Note: A resistance of 6 ohm or greater in the circuit/underhood fuse block will cause the DTC to set.
3. Ignition ON, connect a 20 A fused jumper wire between B+ and the applicable ignition voltage circuit terminal 87 leading to the K20 ECM.
Verify that the applicable scan tool parameter displays between 9-14 V.
瀚慖f the applicable scan tool parameter is less than the specified value, test the ignition voltage circuit for an open/high resistance. If the
circuit tests normal, replace the K20 ECM.
4. Ignition OFF, connect a DMM set to the diode setting between the control circuit terminal 86 and ground. Verify the DMM displays OL.
瀚慖f not the specified value, test the control circuit for a short to ground. If the circuit tests normal, replace the K20 ECM.
5. Ignition ON, verify the DMM displays less than 1 V.
瀚慖f not the specified range, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the
K20 ECM.
6. If all circuits test normal, replace the applicable relay.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* Relay Replacement (Attached to Wire Harness) (See: Power and Ground Distribution/Power Distribution Relay/Service and Repair/Relay
Replacement (Attached to Wire Harness))Relay Replacement (Within an Electrical Center) (See: Power and Ground Distribution/Power
Distribution Relay/Service and Repair/Relay Replacement (Within an Electrical Center))
* Control Module References (See: Testing and Inspection/Programming and Relearning) for ECM replacement, setup, and programming
P1751
DTC P1751
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
DTC P1751
- Shift Valve 1 Performance
Circuit/System Description
The shift solenoid (SS) 1 is part of the control solenoid valve assembly, which has no serviceable parts. SS 1 provides fluid pressure to control the
operation of the clutch select valve 2, which is located in the control valve lower body assembly. SS 1, in conjunction with clutch select valve 2,
controls fluid to the R1 and 4-5-6 clutches. A diagnostic test is performed by the transmission control module (TCM) to determine the state of the
clutch select valve 2. During this diagnostic test, the TCM commands the SS 1 ON, supplying pressure to move the clutch select valve 2 toward its
spring. At the same time, line pressure is elevated slightly to assist the spring side pressure. If the spring is broken, or the clutch select valve 2
cannot move due to another mechanical condition the DTC will set.
Conditions for Running the DTC
* DTCs P0716, P0717, P0722, P0723, P0741, P0742, P1751, P2762, P2763, or P2764 are not set.
* The engine speed is 500 RPM or greater for 5 seconds or greater.
* The transmission fluid temperature (TFT) is 20-130掳C (68-266掳F).
* The calculated throttle position is between 8-90 percent.
