Retarder manual lever open circuit, or short circuit to battery.
â–¶ How to fix
• Check the connectors and wiring • Check the control lever. • Measure the sensor voltage between signal and ground.
What you'll see
No driver-visible symptom recorded.
System reaction
Manual retarder brake will not function as long as the fault is present.
Diagnostic depth
Detection
Impermissible signal from the control lever for manual auxiliary brake control. The sensor voltage level too high. The auxiliary brakelever sensor has an open circuit, or is short circuit to supply voltage.
Possible cause
• Defect wiring: - short circuit between retarder lever signal (pin A5) and supply voltage (+5V or +24 V) - open-circuit on retarder lever signal (pin A5). • Faulty control lever unit • Faulty connectors.