GM Service Manual Online
For 1990-2009 cars only
Table 1: Door locks Typical Symptoms and Causes
Table 2: Remote Control Door Lock Receiver Typical Voltage Measurements

Important: Review the system operation in order to familiarize yourself with the system functions. Refer to the following:

   •  Door Description
   •  Power Windows Description and Operation
   •  Power Door Locks Description and Operation

Visual/Physical Inspection

    • Inspect for aftermarket devices which could affect the operation of the power mirrors and the power windows systems. Refer to Checking Aftermarket Accessories in Wiring Systems.
    • Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.
    • Inspect all related ground points for being clean and tight.

Door locks Typical Symptoms and Causes

Symptom

Possible Cause

LOCK function inoperative from the door switch and the transmitter

    • Open in coil feed or coil ground of door LOCK relay
    • Faulty relay

UNLOCK function operative on the driver's door only from the door switch and the transmitter

    • Open in coil feed or coil ground of door UNLOCK relay
    • Faulty relay

LOCK function inoperative from the transmitter

Open in PNK wire between the remote control door lock receiver and S226

UNLOCK function operative on the driver's door only from the transmitter

Open in RED/WHT wire between the remote control door lock receiver and S222

UNLOCK function inoperative on the driver's door lock from the door switch and operative on the driver's door lock from the transmitter

Open in PNK/GRN wire between the remote control door lock receiver and S228

LOCK function inoperative on the driver's door only from the door switch and the UNLOCK function inoperative from the transmitter

Open in BLK wire between the remote control door lock receiver and G201

UNLOCK function inoperative on the driver's door only from the door switch and all functions inoperative from the transmitter

Open in RED/WHT wire between S221 and S222

Remote Control Door Lock Receiver Typical Voltage Measurements

Terminal/wire

Circuit

Normal Value

Condition

H

Not Used

--

--

G

Not Used

--

--

F

Not Used

--

--

E-RED/WHT

Battery positive voltage

10-14 Volts

--

D

Not Used

--

--

C

Not Used

--

--

B-PNK/GRN

Unlock signal

10-14 Volts

UNLOCK

A-BLU/RED

Unlock control

10-14 Volts (momentary)

UNLOCK

J-BLK/WHT

Ignition positive voltage

10-14 Volts

Ignition ON

K

Not Used

--

--

L-PNK/WHT

Data link connector

10-14 Volts

--

M

Not Used

--

--

N-BLK

Ground

0-1 Volt

--

P-RED/WHT

Battery positive voltage

10-14 Volts

--

R-PNK

Lock control

10-14 Volts

LOCK

S

Not Used

--

--

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom:

    •  Power Mirrors Inoperative
    •  Power Window Inoperative - Passenger Door
    •  Power Window Inoperative - Driver Door
    •  Power Window Express Down Function Inoperative
    •  Power Window Lockout Function Inoperative
    •  Power Door Lock Key Cylinder Switches Inoperative
    •  Power Door Locks Inoperative - One Door or Switch
    •  Symptoms - Keyless Entry in Keyless Entry