GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2005 🢒 STS 🢒 Vehicle Control Systems 🢒 Computer/Integrating Systems 🢒 DTC B3622

Circuit Description

The instrument panel module (IPM) interfaces with an 8-position steering wheel resistive 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 Descriptor

This diagnostic procedure supports the following DTC:

DTC B3622 Steering Wheel Controls Signal Circuit

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 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 doesn't fall into a 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.
    • A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

Diagnostic Aids

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

Switch Function

Resistance Value Range (ohms)

Counts at 14 volts battery voltage

Steering column radio control signal circuit short to B+

--

254-255

Mute/Gap (+)

1248-1292

204-243

Source/Gap (-)

1537-1591

174-203

Voice Req.

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: Cruise Control Connector End Views and Computer/Integrating Systems Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

Important: The Steering Wheel Controls Return parameter proportionally varies 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

    Caution: Refer to SIR Caution 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 .

Did you find and correct the condition?

Go to Step 10

Go to Step 5

5

Test the remote radio control head ACC supply voltage circuit for high resistance. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

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 .

Did 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.

Did you complete the replacement?

Go to Step 10

--

8

Inspect for poor connections at the harness connector of the steering wheel control switch assembly. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did 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 .

Did you complete the replacement?

Go to Step 10

--

10
  1. Reconnect all components.
  2. Use the scan tool in order to clear the DTC.
  3. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

Go to Step 3

System OK