Fault location tree
| ALP 1 | No communication with the control unit |
INSTRUCTIONS
Nothing to report.
| Make sure the diagnostic tool is not the cause of the fault by trying to communicate with another control unit on another vehicle. |
| Check the "low beam" parameter in the Passenger Compartment Central Unit. Is it active? If yes: Carry out a diagnosis of the Protection and Switching Unit. If no: Check the lighting stalk. |
| Check the battery voltage and carry out the necessary work to obtain a compliant voltage (9.5 V < compliant battery voltage < 17.5 V). Make sure there is +12 V before ignition on pin 16, +12 V after ignition on pin 1, and ground on pins 4 and 5 of the diagnostic socket. Repair if necessary. |
| Check the insulation and continuity of the wiring: Headlamp ECU pin 5 → +12 V (lighting stalk in low beam position) |
| If the tool is not the cause and communication cannot be established with any other control unit on the same vehicle, a faulty control unit may be disturbing the K diagnostic line. Disconnect control units one after another to locate this control unit. |
| If the problem persists, contact the Techline. |
AFTER REPAIR
Carry out a check with the diagnostic tool.
Deal with any faults that have been declared.
| ALP 2 | No height correction of one or both headlamps regardless of vehicle load |
INSTRUCTIONS
Only refer to this customer complaint after a complete check with the diagnostic tool.
| Check headlamp initialisation when the low beam headlamps are switched on. |
| Use command AC011 "Headlamp actuator control" to identify the faulty headlamp. Check the front and rear sensor parameters PR002 and PR003 "Initial front and rear heights" are between 30 % < X < 70 % of the faulty control unit. |
| Check the headlamp for mechanical blocking (ball joint disconnected, reflector blocked, actuator seized). |
| Carry out a test by swapping the right and left control units. If the correction moves to the faulty headlamp, contact Techline. If there is no correction on the faulty headlamp: Replace the headlamp. |
AFTER REPAIR
Carry out a check with the diagnostic tool.
Deal with any faults that have been declared.
| ALP 3 | Low beam patterns are aimed too high |
INSTRUCTIONS
Only refer to this customer complaint after a complete check with the diagnostic tool.
| Check that the headlamps are correctly fitted. |
| Check whether the right and left front headlamps light at the same height. If the headlamp heights differ, repeat the initialisation of both control units. |
| Check whether vehicle attitude parameter PR021 "Vehicle attitude" matches the vehicle type LC010. Check whether the initial front and rear heights are correct for the vehicle type using PR004 and PR005 "Initial front and rear heights" between 30 % < X < 70 %. |
| Check the condition of the mechanical system components (sensor bracket, links). Use actuator command AC011 "Headlamp actuator control" and carry out the mechanical adjustment of the headlamps. |
AFTER REPAIR
Carry out a check with the diagnostic tool.
Deal with any faults that have been declared.
| ALP 4 | Sudden drop of one of the two headlamps |
INSTRUCTIONS
Only refer to this customer complaint after a complete check with the diagnostic tool.
| Check the front and rear sensor parameters PR002 and PR003 "Sensor signals": they must be between 0.8 and 11.6 V. Check the position of the actuators PR020 "Actuator position". Check that the position is the same on each side. |
Check the mechanical connections of the sensors:
Repair if necessary. |
| Carry out a test by swapping the two right and left control units. |
| Does the customer symptom persist on the same headlamp? |
| NO | Is the customer symptom present on the other headlamp? Yes → Contact Techline. No → Check the control unit connectors. Repair if necessary |
| YES | Replace the headlamp. |
AFTER REPAIR
Carry out a check with the diagnostic tool.
Deal with any faults that have been declared.
| ALP 5 | Left and right low beams are not aimed at the same height |
INSTRUCTIONS
Only refer to this customer complaint after a complete check with the diagnostic tool.
| Check the vehicle configuration. |
| Check that the headlamps are correctly fitted. |
| Check the "Sensor signal" parameters for sensors PR002 and PR003. |
| Check the condition of the mechanical system components (sensor bracket, links). Repair if necessary. |
| Check the position of actuators PR020 "Actuator position". |
| Perform actuator test AC011 "Headlamp actuator control" and a mechanical headlamp adjustment. |
AFTER REPAIR
Carry out a check with the diagnostic tool.
Deal with any faults that have been declared.
Immobiliser
Diagnostic
For immobilizer diagnosis, see chapter 87B covering the Passenger Compartment Central Unit.Test yourself
A quick Renault Megane quiz: every answer comes with an explanation and a link to the manual page.