Diagnosing Incorrect Function of Steering Wheel Radio Controls – 2004-05 Pontiac GTO

The purpose of this bulletin is to provide assistance for technicians when diagnosing a customer concern of incorrect function of the steering wheel radio controls. It has been found that in most cases, the cause of this condition is a malfunction of the steering wheel switches and is not related to the radio head unit.

To reduce unnecessary radio replacement, please use the following information. These checks are designed to determine if there is a poor connection between the remote control switches and the radio, causing a high resistance which will result in an incorrect function.

Checking Procedure

Important: When you are measuring the resistance, ensure that any probing does not deform the terminals in the vehicle harness.

1. Remove the radio. Use a multi-meter to measure the resistance between pins C11 and C12 in the C1 connector. When no buttons are depressed, the resistance should be approximately 3674 ohms.

2. When each of the switches shown in TABLE 1 is depressed, the resistance measured should be approximately as listed.

Table 1

Switch Resistance Next Up Button 794 Ohms Mute Button 284 Ohms Next Down Button 464 Ohms Volume Up Button 164 Ohms Mode Button 1474 Ohms Volume Down Button 82 Ohms

3. If a high resistance is detected, disconnect all connections, inspect for damage or corrosion, reconnect and measure the resistance again. If the resistance has changed and the correct function of the radio remote switches is achieved, then the condition is considered to be connection-related. Repair or replace as necessary.

If the fault is still present, using the FIGURE 1, check each section of the circuit separately to allow diagnosis of the faulty component.

Only if the fault still persists after performing the above diagnosis should the radio head unit be replaced.