GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The mirror horizontal and vertical position sensors are potentiometers. The Memory Mirror Module (MMM) provides these sensors with a 5 volt reference circuit and a low reference circuit. The MMM monitors the horizontal and vertical position sensor signal circuits which change values based on mirror position. These voltage values are used to determine mirror position and can be set into memory. When the MMM receives a memory recall request, the MMM will control the power mirror to the memory position based on the horizontal and vertical position sensor signal values.

Conditions for Running the DTC

Battery voltage must between 9.0-16.0 volts.

Conditions for Setting the DTC

The horizontal and/or vertical position sensor signal(s) are greater than 4.75 volts or less than 0.50 volts.

Action Taken When the DTC Sets

Memory movements on the malfunctioning axis are disabled.

Conditions for Clearing the DTC

When the fault is no longer present, the MMM changes the current DTC to a history DTC. The MMM will clear the history DTC after 50 fault free ignition cycles.

Diagnostic Aids

    • If DTC B1586 is set by itself, the left horizontal position sensor signal circuit maybe open, shorted to ground or battery
    • If DTC B1596 is set by itself, the left vertical position sensor signal circuit maybe open, shorted to ground or battery
    • If DTC B1616 is set by itself, the right horizontal position sensor signal circuit maybe open, shorted to ground or battery
    • If DTC B1626 is set by itself, the right vertical position sensor signal circuit maybe open, shorted to ground or battery.
    • If DTCs B1586 and B1596 are both set, the left 5 volt reference or low reference circuit(s) maybe open, shorted to ground or battery.
    • If DTCs B1616 and B1626 are both set, the right 5 volt reference or low reference circuit(s) maybe open, shorted to ground or battery.

Step

Action

Value(s)

Yes

No

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 the scan tool, observe the mirror horizontal and vertical position parameters in the Memory Mirror Module (MMM) data list.
  4. Operate both the left and right mirrors through the full range of movements.

Does the scan tool indicate that the left and right mirror horizontal and vertical position parameters are within the specified range?

0.50-4.75 V

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3

Is there a horizontal and vertical DTC set on the same mirror?

--

Go to Step 6

Go to Step 4

4

  1. Turn OFF the ignition.
  2. Disconnect the appropriate 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 mirror position parameter is less than the specified value?

0.50 V

Go to Step 5

Go to Step 8

5

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

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

4.75 - 5.25 V

Go to Step 12

Go to Step 9

6

  1. Turn OFF the ignition.
  2. Disconnect the appropriate mirror.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage between the 5 volt reference circuit at the mirror harness connector and a good ground.

Does the voltage measure within the specified range?

4.75 - 5.25 V

Go to Step 7

Go to Step 10

7

Measure the voltage between the 5 volt reference circuit and the low reference circuit at the mirror harness connector.

Does the voltage measure within the specified range?

4.75 - 5.25 V

Go to Step 12

Go to Step 11

8

Test for a short to voltage on the mirror position signal circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 13

9

Test the mirror position signal circuit for an open, high resistance, short to ground or battery. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 13

10

Test the 5 volt reference circuit for an open, high resistance, short to ground or battery. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 13

11

Test the low reference circuit for an open, high resistance or short to battery. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 13

12

Inspect for poor connections at the harness connector of the power mirror. 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 16

Go to Step 14

13

Inspect for poor connections at the harness connector of the Memory Mirror Module (MMM). 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 16

Go to Step 15

14

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

Did you complete the replacement?

--

Go to Step 16

--

15

Replace the Memory Mirror Module (MMM). Refer to Accessory and Outside Rearview Mirror Module Replacement

Did you complete the replacement?

--

Go to Step 16

--

16

  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