Specialist in the diagnostics and repair of P38 Range Rover electrical and electronic systems
P38 Range Rover
RANGE ROVER P38 Electrical and BECM Problems
The P38 Range Rover, although designed in the 1990’s, was a very revolutionary design for its time and used a lot of electronics to control the vehicle. It is therefore subject to a host of electrical problems, some very simple, others very complex. Many of the problems are centred around the BECM (Body Electronic Control Module). This unit, located under the driver’s seat, controls nearly everything on the vehicle.
Central locking, electric windows, sunroof, lights, indicators, starting, alarm and immobiliser and much more. We have the facilities and equipment to reset, repair, unlock and modify all the settings controlled within the BECM. We can also test all the individual functions of the BECM.
Security and Remote Central Locking
The security system on the P38 is very complex. Each individual key fob has a unique code built into it by the manufacturer. This code is then converted into a fob code and programmed into the BECM.
When the button on the fob is pressed the fob sends a radio signal to the receiver unit in the rear of the vehicle and this receiver sends the signal to the BECM. The BECM then checks the received key code against the stored “Fob Code” and if it matches it will unlock the doors, cancel the alarm and disarm the engine immobiliser.
Range Rover in their wisdom used a very complex design in their remote key fobs. Keys can only be programmed to the vehicle in sets. So, you can’t program keys from two different Range Rovers to one vehicle. Though your Range Rover can be programmed to accept second hand keys, it requires the BECM to be reprogrammed as well. All Car Electrics do not offer this service as a stand-alone BUT if you are sending us your BECM for repair and you have better quality second hand keys we can program the BECM to accept your used keys.
We can also produce new keys to match your P38, cut and programmed to work correctly and at about about half the price of a genuine Range Rover Key. We ideally require an old used key to copy the blade profile and recover the operational transmission code.
New or old, the keys will need to be synchronised to the vehicle. This has to be done when the battery is disconnected, or when introducing new keys to the vehicle.
PLEASE NOTE these are not a flip key, see picture for clarification.
Many non-start situations are caused by the immobiliser function, this is usually either the BECM stored EMS code not matching the Engine ECU, or the BECM going into lock out. Once the vehicle has gone into lockout the central locking won’t work and the immobiliser and alarm are locked on.
BECM Reset & Repair
If the BECM has gone into lock out, many dealers or garages will tell you the BECM is damaged and unrepairable and has to be replaced. With our complex equipment we can connect to the internal electronics within the BECM and reset the lockout. We can also reset and modify all the other parameters stored within the BECM. We can read the EMS code from the engine ECU and re-enter it into the BECM, on early petrol GEMS vehicles we can reset the engine ECU to the learn mode so it accepts the next BECM code it receives. This we can do at the roadside.
Replacing your old BECM
If you need to replace your BECM we can copy all the relevant information from you old BECM and program your new / second hand BECM with all the original parameters like “Fob Code”, EMS codes, Mileage etc. This will then allow your new/used BECM to work correctly on your vehicle.
Diesel Engine Glow Plug Issues
During the last cold snap we were called to quite a few diesel Range Rovers that would not start. A few had been wrongly diagnosed as Engine ECU - BECM synchronisation issues and most turned out to be defective Glow Plugs.
The 6-cylinder BMW engine seems to need all 6 glow plugs working on a cold morning to get it going. If you need to test the glow plugs it’s easier to test them at the Glow Plug relay than at the glow plug. The glow plug relay is bolted to the side of the Engine ECU inside the plastic box, behind the battery. The ecu just lifts out of its box.
Be very careful if you lift out the engine ECU, with the wiring loom connected it makes it all too easy to lay the Engine ECU on top of the battery whilst you fiddle with the glow plug wiring. The slightest slip can see the engine ECU touching the battery + terminal, causing a big flash which burns out connections inside the Engine ECU. On many occasions we have seen P38s that needed major ECU repairs due to shorting out to the battery + terminal.
We see lots of BECMs that have been sent to other "repairers" and when returned the vehicle will not run. The BECM is the brains of the whole vehicle and contains all the Immobilisation codes and the coding required to operate the central locking via the remote fobs.
If these details are erased or changed the BECM will not function correctly. These details can be re-entered but it’s often very difficult to recover the correct information.
Before you send the most complex part of your vehicle to some unknown repairer remember the saying, if you think a Professional is expensive see what an Amateur can cost you!
We now offer a mobile P38 BECM Immobilisation reset service for £150 plus travelling expenses at £1 a mile (one direction only) from our post code RH16 3PD to your post code, as calculated by AA autoroute, and a Postal Service (see our Home page for more info). We will aim to turn around any BECM sent to us by Post/Courier within 48 hours depending when we receive it and return all reset BECMs with a printed report of all the internal settings.
Range Rovers suffer quite a lot of problems with synchronisation errors. The security code stored within the engine ECU must be matched by the code sent from the BECM.
On Petrol Gems vehicles this Synchronisation is indicated by an orange check engine light on the instrument panel which should illuminate when turning the ignition on. If this light doesn't illuminate it means the Engine ECU is not Synched with the BECM and it won’t start. On later Petrol engine (Thor) and Diesel engine P38 Range Rovers you don’t get a check engine light.
Many non-start problems are caused by the BECM forgetting the security code it should send to the engine control unit to enable the engine to run. This is usually caused by the age of the components within the BECM. To overcome this problem we can offer Re- synchronisation at the roadside or for those further away we can offer the hire of a simple tool that will Resynchronise the BECM and Engine ECU. The device just plugs into the diagnostic socket in the passenger foot well, everything else is automatic
ENGINE ECU AND BECM SWAPS
We can program any BECM to any engine ECU, or we can recover the security codes from a second hand engine ECU and program your original BECM.
We can also re code a used BECM to match your original BECM, recover and change EKA codes and turn off the Immobiliser and alarm.
Range Rover understood that the key fob might not always work due to a flat battery or damage, so they included a 'get you started' function. The BECM has a Security number called the EKA (Emergency Key Access) code stored in it.
This number can be entered by turning the driver's door lock backwards and forwards the correct number of times to match the EKA code. This then turns the alarm and Immobiliser off. Many owners have either lost or have invalid EKA codes.
The good news is All Car Electrics can either retrieve or reset the stored EKA code.
Click here to view or download instructions on entering the EKA code.
Range Rover made the alarm and immobiliser self arming, so when you get out and lock the vehicle, the alarm and immobiliser are turned on automatically. The only way to reset the alarm and immobiliser is by using the remote key fob or entering the EKA code via the driver's door lock. If the remote fob fails, or you don’t have the EKA code your vehicle is dead.
We can program the BECM so the alarm and immobiliser doesn’t self arm, therefore it won't immobilise itself every time you leave the vehicle. This also means that aftermarket keys can be used. We can also retrieve the EKA code from the BECM or reprogram a new EKA code with a more memorable number.
Please note the Alarm and immobiliser will still arm if you lock the vehicle with the remote fob button.
The Immobiliser function works by the individual engine control unit requiring a valid EMS code to be received from the BECM to enable the engine to start. This code, unique to the engine control unit, is on all P38s except early petrol variants fitted with the GEMS Fuel injection system. The GEMS system has a learn facility that accepts the first BECM EMS code it receives when new.
GEMS system Immobiliser Bypass
Early petrol engine Range Rovers were fitted with the Lucas Gems Fuel injection system. We now have the means to enable you to run your fuel injection system without a BECM being fitted.
A small unit called a Geko is wired into the Gems ECU, it takes just three wires to connect up.
The Gems ECU must then be put into learn mode using a diagnostic scanner or a Synchronising tool connected to the diagnostic socket. After the Gems Unit is in the Learn mode it will accept the first code it receives. The code from the generator is then accepted and the Gems will run every time the ignition is turned on.
If your Range Rover is a stripped out off roader with no diagnostic socket, the GEMS ecu could be fitted into another Range Rover to be put into Learn mode then fitted back in the original vehicle.
GEMS engine (get you home emergency start kit) from All Car Electrics
If you have a P38 Range Rover, and you have had the misfortune of the vehicle immobiliser preventing you from starting the engine, i.e., Vehicle immobilised, Key code lock out, or the check engine light not coming on or any other BECM orientated non start problem we now have an emergency kit of parts that you the owner can temporarily fit to the vehicle, enabling the vehicle to be driven home, or to a garage etc.
The kit of parts is a modified Engine ECU and two link wires. The only tools required are a “Philips screwdriver” to remove the engine ecu box plastic cover. The fitting of these parts should take less than 10 minutes. Once fitted the engine can be started and driven as normal. This is intended as a get you home tool, and not a permanent fix.
Here at All Car Electrics we understand Range Rover P38s and offer a range of Services to suit owners wherever they live. In addition to Workshop and Mobile repairs we can mend BECMs and ECUs by Post and are proud that due to the speed and reliability of our service we have satisfied customers from all over the world.
For more information, or if you have a question or problem with your P38, please give us a ring or complete the online Contact Form. You are in safe hands with All Car Electrics.