Chevrolet Silverado / GMC Sierra. Service manual — part 2659

Diagnostic Fault Information

Circuit/System Description

The Driver Door Switch (DDS) and Passenger Door Switch (PDS) determine the position of the
outside rearview mirrors based on inputs from two mirror position sensors, one for vertical
position, the other for horizontal position. Five volts are applied to each sensor through a shared
5-volt reference circuit and a shared low reference circuit supplies ground. Each sensor has an
individual signal circuit which provides position voltage to the DDS/PDS.

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

B1580

An improper voltage level is seen on the Driver/Passenger Mirror Horizontal Position Sensor
Signal circuit.

B1590

An improper voltage level is seen the Driver/Passenger Mirror Vertical Position Sensor Signal
circuit.

Action Taken When the DTC Sets

Mirror movement is suspended so long as the fault is present.

Conditions for Clearing the DTC

Circuit

Short to

Ground

Open/High

Resistance

Short to

Voltage

Signal

Performance

5-Volt Reference

B1580,

B1590

B1580, B1590

B1580,

B1590

-

Driver/Passenger Mirror
Horizontal Position Sensor
Signal

B1580

B1580

B1580

-

Driver/Passenger Mirror
Vertical Position Sensor Signal

B1590

B1590

B1590

-

Low Reference

B1580,

B1590

B1580, B1590

B1580,

B1590

-

2008 Chevrolet Silverado 1500

2008 ACCESSORIES & EQUIPMENT Mirrors - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

A current DTC will clear when the fault is no longer present.

A history DTC will clear after 40 malfunction-free ignition cycles.

Reference Information

Schematic Reference

Outside Rearview Mirror Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Outside Mirror Description and Operation (Heated Mirrors) or Outside Mirror
Description and Operation (Power Mirrors)

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool References

Control Module References For Scan Tool Information.

Circuit/System Verification

Ignition ON, observe the scan tool Mirror Horizontal Position and Mirror Vertical Position
parameters. The reading should be between 0.2-4.8 volts and change as the mirror is moved, left,
right, up, and down.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector X7 at the appropriate door switch.

2. Ignition ON, verify a test lamp does not illuminate between the following circuit terminals

and ground:

2008 Chevrolet Silverado 1500

2008 ACCESSORIES & EQUIPMENT Mirrors - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

5-volt reference circuit terminal 7

Signal circuit terminal 4

Signal circuit terminal 5

Low reference circuit terminal 10

If the test lamp illuminates, test the appropriate circuit for a short to voltage.

3. Ignition OFF, test for infinite resistance between the following circuits and ground:

5-volt reference circuit terminal 7

Signal circuit terminal 4

Signal circuit terminal 5

Low reference circuit terminal 10

If less than the specified value, test the appropriate circuit for a short to ground.

4. Test for 4K-7K ohms of resistance between the 5-volt reference circuit terminal 7 and the

low reference circuit terminal 10.

If not within the specified range, test the 5-volt reference circuit and the low reference
circuit for an open/high resistance. If the circuits test normal, test or replace the
rearview mirror motor.

5. Test for 1K-7K ohms of resistance between the 5-volt reference circuit terminal 7 and the

signal circuit terminal 4.

If not within the specified range, test the signal circuit for an open/high resistance. If
the circuits test normal, test or replace the rearview mirror motor.

6. Test for 1K-7K ohms of resistance between the 5-volt reference circuit terminal 7 and the

signal circuit terminal 5.

If not within the specified range, test the signal circuit for an open/high resistance. If
the circuits test normal, test or replace the rearview mirror motor.

7. If all circuits test normal, replace the appropriate door switch.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Outside Rearview Mirror Motor Replacement

Control Module References for DDS or PDS replacement, setup, and programming

DTC B1640

Diagnostic Instructions

2008 Chevrolet Silverado 1500

2008 ACCESSORIES & EQUIPMENT Mirrors - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

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 Descriptors

DTC B1640 01

Mirror Heater Circuit Short to Battery

DTC B1640 02

Mirror Heater Circuit Short to Ground

Diagnostic Fault Information

Circuit/System Description

The Driver Door Switch (DDS) and Passenger Door Switch (PDS) supply voltage to the outside
rearview mirror heater elements upon receipt of a serial data message from the HVAC module
indicating that the rear defrost system is active. The door switch supplies B+ through the
driver/passenger mirror heating element supply voltage circuit when a request is seen. Ground is
applied through the driver/passenger mirror heating low reference circuit.

Conditions for Running the DTC

The heated mirrors or commanded ON.

Conditions for Setting the DTC

B1640 01

A short to voltage is detected on the mirror heating element supply voltage circuit while the
heated mirrors.

Circuit

Short to

Ground

Open/High

Resistance

Short to

Voltage

Signal

Performance

Mirror Heating Element
Supply Voltage

B1640 02

1

B1640 01

-

Low Reference

-

1

1

-

1. Heated Mirror Malfunction

2008 Chevrolet Silverado 1500

2008 ACCESSORIES & EQUIPMENT Mirrors - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado