Technical information & repair service
Land Rover ALM / CH12 / DH12 Immobiliser
After a battery replacement, deep discharge or severe voltage fluctuation, the immobiliser in certain Land Rover models may fail. We inspect the control unit, recover available data and, in many cases, restore vehicle operation.
Common trigger
A flat or disconnected vehicle battery, or a severe undervoltage condition.
Possible effects
The remote control, central locking or immobiliser may stop responding.
Our approach
Data analysis, data recovery, repair or replacement with a robust alternative solution.
What happens when this fault occurs?
The ALM, CH12 and DH12 modules were introduced as successors to earlier Lucas immobiliser systems. Based on our long-term workshop experience, critical voltage conditions can cause the processor to enter an unintended state and damage important memory data.
The risk is especially high when battery voltage drops slowly or the vehicle electrical system becomes unstable during battery replacement. Depending on the extent of the data corruption, only the remote key fobs may stop working at first. In more severe cases, the complete module may stop responding.
Typical symptoms
- The remote key fob no longer locks or unlocks the vehicle.
- The engine does not start even though the key itself is intact.
- The central locking system works intermittently or not at all.
- The immobiliser module can no longer be reached by diagnostic equipment.
- The fault occurred directly after a flat battery, jump start or battery replacement.
What we check
- Condition and readability of the stored data
- Communication and basic operation of the module
- Options for recovering the original vehicle data
- Suitability of a repaired or alternative replacement solution
Repair instead of replacing the complete vehicle electronics
Replacing several matched control units can be complex and expensive. We therefore first try to recover or restore the data from the original module. If the original unit can no longer be used reliably, a suitable replacement solution may be possible depending on the vehicle and the fault.
A binding assessment can only be made after the module and the relevant vehicle information have been inspected.
Immobiliser failure?
Please send us the vehicle model, model year, symptoms and the circumstances under which the fault occurred. It is particularly helpful to know whether the failure followed a deep discharge, jump start or battery replacement.
Go to the enquiry and order page
Please do not send control units without contacting us first.