For 1990-2009 cars

### Circuit Description

The instrument panel module (IPM) interfaces with an 8-position steering wheel resistor ladder. These switches are used for entertainment purposes and cruise control purposes if the vehicle is equipped with adaptive cruise control. The steering wheel switch network is fed by the remote radio control head ACC supply voltage. The return signal to the IPM is provided by steering column radio control signal circuit. The output voltage must be read by an A/D in order to carry out a ratiometric read which will be used to determine which, if any, switch has been activated.

### DTC Descriptors

The diagnostic procedure supports the following DTCs:

Steering Wheel Controls Signal Circuit

This vehicle has DTCs including the DTC symptoms. For more information on DTC symptoms, refer to DTC Symptom Description.

DTC Symptom | DTC Symptom Descriptor
--- | ---
01 | Short to Battery
08 | Signal Invalid
59 | Circuit Protection Time-Out

### Conditions for Running the DTC

• | Voltage supplied to the module is in the normal operating voltage range of 9-16 volts.

• | IPM in Accessory, Run or Crank power modes.

### Conditions for Setting the DTC

#### B3622 01

The IPM detects that a short to voltage on steering column radio control signal circuit for more than 5 seconds.

#### B3622 08

The IPM detected signal from the steering column radio control signal circuit does not fall into the calibrated range.

#### B3622 59

The IPM detects that any of the steering wheel control switches is stuck for more than 30 seconds.

### Action Taken When the DTC Sets

#### B3622 01 and 08

The IPM does not react to any switch inputs.

#### B3622 59

The IPM does not react to any switch inputs of equal or lower priority. If 2 switches are closed at the same time the IPM will read the least resistive path, so that switch takes precedence over the other one.

### Conditions for Clearing the DTC

• | A current DTC clears when the malfunction is no longer present.

• | When the ignition cycle counter has reached the newly set threshold and no trouble occurs repeatedly, the history DTC will be cleared.

### Diagnostic Aids

The following are the correct resistance value ranges and counts displayed by IPM. The counts displayed by the scan tool vary proportionally with battery voltage.

Switch Function | Resistance Value Range (Ω) | Counts at 14 Volts Battery Voltage
--- | --- | ---
Steering column radio control signal circuit short to B+ | -- | 244-255
Mute/Gap (+) | 1248-1292 | 204-243
Source/Gap (-) | 1537-1591 | 174-203
Voice Requirement | 1879-1945 | 147-173
Preset Seek | 2346-2428 | 118-146
Vol. Up | 3048-3156 | 92-117
Vol Dn. | 4208-4356 | 65-91
Seek Up | 6537-6767 | 38-64
Seek Dn. | 13397-13876 | 12-37
No Switch Active | ∞ | 0-11

Step | Action | Yes | No
--- | --- | --- | ---
Schematic Reference: Cruise Control Schematics Connector End View Reference: Component Connector End Views
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 | Note: The Steering Wheel Controls Return parameter varies proportionally with battery voltage. They will not necessarily follow the values from the table.

1. Turn ON the ignition, with the engine OFF.
2. Observe the Steering Wheel Controls Return parameter under instrument panel module (IPM) Data Display Inputs.
3. Compare the parameter values with the values provided in Diagnostic Aids for every switch position.

Are all the values correct?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3 |

Warning: Refer to SIR Warning in the Preface section.

1. Turn OFF the ignition.
2. Disconnect the steering wheel control switch assembly.
3. Measure the resistance between the remote radio control head ACC supply voltage circuit and the steering column radio control signal circuit at the steering wheel control switch.
4. While measuring the resistance, press each of the steering wheel control switches.

Does the resistance toggle between infinite and the range specified in Diagnostic Aids for each switch?

Go to Step 4

Go to Step 8

4 |

1. Disconnect the IPM.
2. Test the steering column radio control signal circuit for a short to voltage or high resistance. Refer to Circuit Testing and Wiring Repairs.

Do you find and correct the condition?

Go to Step 10

Go to Step 5

5 | Test the remote radio control ACC supply voltage circuit for high resistance. Refer to Circuit Testing and Wiring Repairs. Are there any DTCs that have not been diagnosed? | Go to Step 10 | Go to Step 6
6 | Inspect for poor connections and terminal tension at the harness connector of the IPM. Refer to Testing for Intermittent Conditions and Poor Connections. Do you find and correct the condition? | Go to Step 10 | Go to Step 7
7 | Replace the IPM. Refer to Control Module References for replacement, setup, and programming. Is the replacement complete? | Go to Step 10 | --
8 | Inspect for a poor connection at the harness connector of the steering wheel control assembly. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs. Do you find and correct the condition? | Go to Step 10 | Go to Step 9
9 | Replace the steering wheel control switch assembly. Refer to Steering Wheel Control Switch Assembly Replacement. Is the replacement complete? | Go to Step 10 | --
10 |

1. Reconnect all components.
2. Clear the DTCs with the scan tool.
3. Operate the vehicle under conditions when DTC runs as specified in supporting documents.

Does the DTC set again?

Go to Step 3

System OK