Chevrolet Silverado / GMC Sierra. Service manual — part 1695

1. Ignition On. Measure and record the voltage at the battery terminals. Verify that the battery

voltage is 11-15 volts. Repeat with the engine running.

If the battery voltage is not within the specified range, go to Charging System Test.

2. Engine running. Observe the scan tool Ignition 1 Signal parameter in the ECM data list.

Verify that the scan tool displays a value that is within 1 volt of the battery voltage recorded
in step 1.

If the scan tool parameter is not within the specified range, replace the ECM.

3. Go to Diagnostic Aids.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for ECM replacement, setup, and programming

DTC P0615

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC P0615

Starter Relay Control Circuit

Diagnostic Fault Information

Circuit/System Description

When the ignition switch is placed in the START position, a discrete signal is supplied to the
body control module (BCM) notifying it that the ignition is in the START position. The BCM

Circuit

Short to

Ground

Open/High

Resistance

Short to

Voltage

Signal

Performance

STRTR Relay Control

P0615

P0615

P0615

-

Ground

-

P0615

-

-

2008 Chevrolet Silverado 1500

2008 ENGINE Engine Electrical - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

then sends a message to the engine control module (ECM) that crank has been requested. The
ECM then verifies that the clutch is depressed for the manual transmission or that the automatic
transmission is in Park or Neutral. If it is, the ECM then supplies 12 volts to the control circuit of
the STRTR relay. When this occurs, battery voltage is supplied through the switch of the STRTR
relay to the S terminal of the starter solenoid. The ECM monitors the voltage on the STRTR relay
control circuit. If the ECM detects that the STRTR relay control circuit is open or shorted, then
DTC P0615 sets.

Conditions for Running the DTC

The Ignition is in the START position.

The system voltage is between 9.5-18 volts.

Conditions for Setting the DTC

The ECM detects improper voltage on the control circuit of the STRTR relay.

Action Taken When the DTC Sets

DTC P0615 is a C type DTC.

Conditions for Clearing the DTC

DTC P0615 is a C type DTC.

Diagnostic Aids

Verify that the ground connection for the STRTR relay ground circuit is clean and tight.

Inspect the terminals for the STRTR relay in the underhood fuse block for poor connections.

Reference Information

Schematic Reference

Starting and Charging Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Starting System Description and Operation

2008 Chevrolet Silverado 1500

2008 ENGINE Engine Electrical - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Ignition ON. Verify that no theft deterrent or automatic transmission DTCs are set that

would cause the ECM to disable engine starting.

If any DTCs are set that would cause the ECM to disable starting, then refer to
Diagnostic Trouble Code (DTC) List - Vehicle .

2. Clear the DTCs. Start the engine. Verify that DTC P0615 does not set.

Circuit/System Testing

1. Ignition OFF, test for less than 5 ohms between the relay ground circuit terminal 85 and

ground.

If greater than the specified range, test the ground circuit for an open/high resistance.

2. Ignition OFF. Connect a test lamp between the control circuit terminal 86 and the ground

circuit terminal 85. Turn the ignition to the start position. The test lamp should turn ON
when the ignition is in the START position, and OFF in all other positions.

If the test lamp is always on, test the control circuit for short to voltage. If the circuit
tests normal, replace the ECM.

If the test lamp is always off, test the control circuit for a short to ground or an
open/high resistance. If the circuit tests normal, replace the ECM.

3. If all circuits test normal, test or replace the STRTR relay.

Component Testing

STRTR Relay

1. Ignition OFF, disconnect the STRTR relay.

2. Test for 60-180 ohms between terminals 85 and 86 of the relay.

2008 Chevrolet Silverado 1500

2008 ENGINE Engine Electrical - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

If not within the specified range, replace the STRTR relay.

3. Test for infinite resistance between the following terminals:

30 and 86

30 and 87

30 and 85

85 and 87

If not the specified value, replace the relay.

4. Install a 20 amp fused jumper wire between relay terminal 85 and 12 volts. Install a jumper

wire between relay terminal 86 and ground. Test for less than 2.0 ohms between terminals
30 and 87 of the relay.

If greater than specified range, replace the relay.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Relay Replacement (Attached to Wire Harness) or Relay Replacement (Within an
Electrical Center)

Control Module References for ECM replacement, setup, and programming

DTC P0621

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC P0621

Generator L-Terminal Circuit

Diagnostic Fault Information

Circuit

Short to

Ground

Open/High

Resistance

Short to

Voltage

Signal

Performance

Generator Turn On Signal

P0621

P0621

P0621

-

2008 Chevrolet Silverado 1500

2008 ENGINE Engine Electrical - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado