Circuit/System Testing

Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the T4M Radio Antenna. It may take up to 2 min for all vehicle systems to power down.
Ignition ON, A11 Radio ON.
Verify a test lamp illuminates between terminal 1 ground.
- If the test lamp does not illuminate
1. Ignition OFF, remove the test lamp, disconnect the harness connector at the A11 Radio.
2. Test for infinite resistance between the control circuit and ground.
  - If less than infinite resistance, repair the short to ground on the circuit.
  - Go to next step: If infinite resistance
3. Test for less than 2 Ω in the control circuit end to end.
  - If 2 Ω or greater, repair the open/high resistance in the circuit.
  - If less than 2 Ω, replace the A11 Radio.
- Go to next step: If the test lamp illuminates
Ignition OFF, disconnect the harness connector at the A11 Radio. Ignition ON.
Test for less than 1 V between the signal circuit terminal 38 and ground.
- If 1 V or greater
  Repair the short to voltage on the circuit.
- Go to next step: If less than 1 V
Ignition OFF.
Test for infinite resistance between the signal circuit terminal 38 and ground.
- If less than infinite resistance
  Repair the short to ground on the circuit.
- Go to next step: If Infinite resistance
Test for less than 2 Ω between the T4M Radio Antenna terminal 2 and the A11 Radio terminal 38.
- If 2 Ω or greater
  Repair the open/high resistance in the circuit.
- Go to next step: If less than 2 Ω
Replace the T4M Radio Antenna.
Ignition ON, A11 Radio ON.
Verify station reception is normal when tuned to several known good AM and FM stations.
- If AM or FM reception is poor.
  Replace the A11 Radio.
- Go to next step: If reception is normal.
All OK.