GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The memory mirror module (MMM) receives inputs from the mirror position sensors during the following functions:

    • Memory recall
    • Memory seat
    • Easy exit

The potentiometers in the position sensors vary in resistance as the motors move the mirror. The MMM receives a variable voltage input depending on the resistance of the potentiometer. During memory set, the MMM records the voltages across the mirrors. During memory recall, the MMM moves the mirror motors until the voltage across each potentiometer matches the recorded voltage. During normal operation, the mirror position sensors are checked against out-of-range limits.

Conditions for Running the DTC

DTCs B1982 and B1983 are not set.

Conditions for Setting the DTC

The outside rear view mirrors vertical or horizontal position sensor input voltage is greater than 4.75 volts.

Action Taken When the DTC Sets

The memory mirror module (MMM) will disable the affected motor during memory recall.

Conditions for Clearing the DTC

    • The memory mirror module (MMM) no longer detects the position sensor failure.
    • 50 consecutive ignition cycles have been recorded without the DTC being detected.

Diagnostic Aids

    • If DTC B2145 is set by itself, the Left Mirror Vertical Position Sensor Signal circuit may be short to battery positive voltage.
    • If DTC B2147 is set by itself, the Left Mirror Horizontal Position Sensor Signal circuit may be short to battery positive voltage.
    • If DTC B2149 is set by itself, the Right Mirror Vertical Position Sensor Signal circuit may be short to battery positive voltage.
    • If DTC B2151 is set by itself, the Right Mirror Horizontal Position Sensor Signal circuit may be short to battery positive voltage.
    • If DTCs B2145 and B2147 were set together, the Low Reference circuit between splice S226 and the LH outside mirror may be open.
    • If DTCs B2149 and B2151 were set together, the Low Reference circuit between splice S226 and the RH outside mirror may be open.
    • If DTCs B2145, B2147, B2149 and B2151 were all set, the following may have occurred:
       - The Low Reference circuit between the MMM and splice S226 may be open.
       - The 5 Volt Reference circuit may be short to battery positive voltage.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. Tests for the proper operation of the circuit in the high voltage range.

  2. Tests for the proper operation of the circuit in the low voltage range. If the fuse in the jumper opens when you perform this test, the signal circuit is shorted to voltage.

  3. Tests for a short to ground in the 5 volt reference circuit.

Step

Action

Value(s)

Yes

No

Schematic Reference: Outside Rearview Mirror Schematics

1

Did you perform the Door Systems Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - Door Systems

2

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, observe the appropriate mirror position parameter in the Memory Mirror Module data list.

Does the scan tool indicate that the appropriate mirror position parameter is within the specified range?

0.25 - 4.75 volts

Go to Diagnostic Aids

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Disconnect the appropriate outside mirror.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the appropriate mirror position parameter.

Does the scan tool indicate that the appropriate mirror position parameter is greater than the specified value?

4.75 volts

Go to Step 4

Go to Step 8

4

  1. Turn OFF the ignition.
  2. Connect a 3 amp fused jumper wire between the signal circuit of the appropriate mirror position sensor and the low reference circuit of the appropriate mirror position sensor.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the mirror position sensor parameter.

Does the scan tool indicate that the mirror position sensor parameter is less than the specified value?

0.25 volts

Go to Step 5

Go to Step 9

5

  1. Turn OFF the ignition.
  2. Disconnect the fused jumper wire.
  3. Connect a 3 amp fused jumper wire between the 5 volt reference circuit of the appropriate mirror position sensor and the signal circuit of the appropriate mirror position sensor.
  4. Turn ON the ignition, with the engine OFF.
  5. With a scan tool, observe the mirror position sensor parameter.

Does the scan tool indicate that the mirror position sensor parameter is greater than the specified value?

4.75 volts

Go to Step 7

Go to Step 6

6

Test the 5 volt reference circuit of the appropriate mirror position sensor for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 12

7

Test the 5 volt reference circuit of the appropriate mirror position sensor for a short to voltage, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 11

8

Test the signal circuit of the appropriate mirror position sensor for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 12

9

Test the signal circuit of the appropriate mirror position sensor for a short to voltage, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 10

10

Test the low reference circuit of the appropriate mirror position sensor for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 12

11

Inspect for poor connections at the harness connector of the Power Mirror Motor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 13

12

Inspect for poor connections at the harness connector of the memory mirror module (MMM). Refer to Testing for Intermittent Conditions and Poor Connections a and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 14

13

Replace the power mirror motor. Refer to Outside Rearview Mirror Motor Replacement .

Did you complete the replacement?

--

Go to Step 15

--

14

Replace the memory mirror module (MMM). Refer to Memory Mirror Module Replacement .

Did you complete the replacement?

--

Go to Step 15

--

15

  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

--

Go to Step 2

System OK