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GEMS, Re-programming or Mobi4
Order - Reprogram
Send your GEMS unit for re-programming on our test bench and it will be returned to you no longer requiring the input of a security code to start the engine.
When GEMS units were manufactured, they did not require a security code to start an engine. As robust immobilisation was the norm in almost all markets, GEMS units were programmed to accept a matching security code before the engine could run. At that time, the programming of a GEMS unit for robust immobilisation was believed to be irreversible. It has taken a quite lot of research and development to establish the way to reprogram a GEMS unit so that it will no longer require the input of a security code to run an engine. For after market repairers this is a no-brainer. Arrive at the stranded vehicle, open the bonnet (hood), remove the GEMS, fit your GEMS, remove the start relay and bridge 30 and 87 with a start push button on long wires. Close the bonnet (hood), get into the driver's seat, turn the ignition key on and push the start button and the engine starts and you are away. If the BECM is really dead, you may have to also remove the ignition on relay and place a bridge between terminals 30 and 87 to turn the ignition on. Drive back to your workshop, determine what went wrong and fix it there. Quick and easy.
Reprogramming can be costly outside of Australia because of the expensive freight/postage and insurance costs of a plus 2 Kg parcel. Contact us for a quote.
Order – Mobi4
Order a Mobi4 and fit it to your vehicle (*or stand-alone engine). After the GEMS has been introduced to the Mobi4 with a ‘security code re-learn’, the engine can be started and will run in your Range Rover, transplanted into another vehicle or used as a stand-alone without needing a BECM to supply the coded bit stream to the GEMS. Mobi4 overcomes most of the immobilization problems with the GEMS. The engine can be started and will run with the BECM in alarm, dead or even removed from a Range Rover because the Mobi4 sends the coded bit stream to the GEMS. When the BECM is in alarm, immobilized, dead or removed then bypassing the starter relay and ignition ON circuits will be required to initiate the ignition on and starting. Details for doing this are in the By-pass instructions tab.
Mobi4 is a completely new design with an operational temperature range from below freezing to +120 degrees Celsius.
Order – Mobi4 & Relearn Tool
If you require, we can send to you, on loan, a Security Relearn Tool so that you can do a security relearn yourself. When you have finished, return the tool to us for a full refund of your $200.00 deposit. See Security Relearn Tool tab for more information. * Note: The Security Relearn tool will only work with the GEMS in a Range Rover. It must be able to communicate with both the BECM and the GEMS for it to work.
Before you order the Relearn Tool - Check the diagnostic socket in your vehicle for any signs of moisture or corrosion. Use a mirror and torch (flash light) to illuminate the socket and visually inspect it. If there are any signs of water or corrosion, please order and fit a Data replacement diagnostic connector. Connecting the plug of our Security Relearn Tool into a contaminated diagnostic socket will contaminate its plug and require, on its return to us, cleaning (or replacement if water has penetrated inside) at an additional cost, as we do not want to send out a dead tool or to contaminate the diagnostic socket in another vehicle. Refer to DATA.
Connecting Mobi4 into the wiring on top of the GEMS
Mobi4 is a new design and is manufactured with the highest temperature components that can be sourced here in Australia. In testing it has an operational temperature range of below freezing to +120 degrees C and we believe that the Mobi4 will overcome the hot restart issues that the Mobi2 had when fitted at the GEMS. Feedback please.
Power – ignition on. Solder the Mobi4 red power wire to the large brown wire with the orange trace in the 18-pin black connector at the end of the ECM (pin 7).
Security code sending – bit stream. As the original coded bit stream from the BECM is no longer used, this operation requires that the black wire in Pin 26 of the 36-pin red connector be cut.Solder the black wire going to the GEMS to the white (coded bit stream out) wire from the Mobi4 and insulate the connection. Tie back and insulate the un-used black coded bit stream wire from the BECM.
Earth – Shorten the long black earth wire of the Mobi4 and solder it to any one of the four black wires in the 18-pin black connector at the end of the GEMS.
Once the Mobi4 has been wired to the GEMS unit, a Security Re-learn will have to be performed with the GEMS. This is done so that the GEMS can learn the new security code that is being sent from the Mobi4.
A security re-learn requires the use of a diagnostic tool capable of putting the GEMS into the security re-learn mode. Your repairer can probably do this for you as most Land Rover aftermarket repairers have these diagnostic tools. Or you can order a loan Security Relearn Tool and do your own security relearn.
Note: Our Security Relearn tool will only work with the GEMS in a Range Rover. It must be able to communicate with both a BECM that is not in alarm or immobilised and the GEMS for it to work.
Note: I have had one GEMS unit that would not go into Security Relearn, I have had reports of only a very few others.
Below is the Image for the same.
Connecting Mobi4 at the BECM
Power – ignition on. The red wire requires power when the ignition is switched on. Solder the red wire from the Mobi4 to only one of the BECM wires below and insulate the connection:
The white/purple wire from pin 1 of the 12 way grey connector (C-323) on the front (electro-chromatic rear view mirror) The green wire from pin 4 of the 4 way natural connector (C-324) on the front (illuminated mirrors in sun visors) The green/grey wire from pin 1 of the 14 way yellow connector (C-120) on the front (SRS) Any of the white wires from pins 1, 2 or 3 on the 12 way white connector (C-625) on the inside The white wire from pin 9 of the 10 pin white connector (C-258) on the rear
Note: not all Range Rovers have all of these wires and their associated features
Earth – The long black wire from the Mobi4 is connected to earth. You may solder it to the thick black earth wire on the outside rear of the BECM or fit an eye terminal, drill a hole in the seat base, remove the paint from around the hole and attach the eye terminal with a self tapping screw or nut and bolt.
Note: I do not recommend that the black earth terminal at the rear of the BECM be removed as this will turn off the BECM and you may have problems when it is reconnected.
Refer to EKA, BECM Power Down and Power Up tab in BECM programming.
Security code – Pin 5 of the 16-pin green connector (C-112) on the front of the BECM has the black wire that sends out the coded bit stream to the GEMS. (If you have to drive to a repairer to have, a security re-learn done then leave this last connection to be made at or by the repairer.) Cut the black wire between the BECM and the GEMS; leave enough length on the BECM end to reconnect it later if required. Solder the white wire from the Mobi4 to the black wire going to the GEMS and insulate the connection. Tie back and insulate the end of the un-used black wire from the BECM.
Once the Mobi4 has been wired to the front of the BECM, a Security Re-learn will have to be performed with the GEMS. This is done so that the GEMS can learn the new security code that is being sent from the Mobi4. A security re-learn requires the use of a diagnostic tool capable of putting the GEMS into the security re-learn mode. Your repairer can probably do this for you as most Land Rover aftermarket repairers have these diagnostic tools. Or you can order a loan Security Relearn Tool and do your own security relearn. * Note: The Security Relearn tool will only work with the GEMS in a Range Rover. It must be able to communicate with both a BECM that is not in alarm or immobilised and the GEMS for it to work.
Note: I have had one GEMS unit that would not go into Security Relearn; I have had reports of only a few others.
However - if you are encountering any problems with the gold plating on the terminals connecting the BECM and the GEMS the bit stream from the Mobi4 may not reach the GEMS or the OK from the GEMS may not reach the BECM. Refer to the intermittent non-start tab for terminals to treat.
Install by-pass switches so that if trouble strikes you are prepared. Connect an ON/OFF switch and a normally open push button between the wires as shown below. You will need to add two wires to the BECM.
Solder the by-pass wires to the wires near the connectors and insulate the solder joins. Fit two long wires so that the switch and push button can be located near the front of the seat for easy access.
To switch on the Ignition Relay in the engine bay fuse box the white wire on pin 8 of the 10 pin white connector (C-258) on the rear of the BECM has to be connected to the white wire on pin 9 of the 14 pin yellow connector (C-120) on the front of the BECM. When the ignition key is turned to the ‘Ignition ON’ position and the by-pass switch is ON the signal goes around the BECM to operate the Ignition Relay. With the Ignition by-pass switch in the off position the BECM operation is normal.
To operate the Starter Relay in the engine bay fuse box the white wire with the red trace on pin 6 of the 20 pin yellow connector (C-257) on the outside of the BECM (under the fuses) has to be connected to the white wire with the red trace on pin 2 of the 10 pin yellow connector (C-113) on the front of the BECM. When the ignition key is turned to the ‘Start’ position and the by-pass push button is operated, the signal goes around the BECM to operate the Start Relay and cranks over the engine.
Caution: The engine will start with the transmission in gear and the vehicle will move.
Before actuating the bypass push button, ensure that both handbrake and footbrake are on. Manual transmission in neutral and clutch depressed and automatic gearbox is in either neutral or park.
Security Relearn Tool
Note: The Security Relearn tool will only work with the GEMS in a Range Rover. It must be able to communicate with both the BECM and the GEMS for it to work. The BECM cannot be in alarm or immobilised.
If you are going to transplant the engine into another type of vehicle or use it as a stand-alone please connect the Mobi4 at the GEMS unit and do the security relearn before removing the GEMS and engine from the Range Rover.
Insure that the coded bit stream wire from the BECM is disconnected from the GEMS otherwise the GEMS will receive codes from both and be confused.
Connect the diagnostic plug from the Security Relearn Tool to the vehicle's clean and dry diagnostic socket*.
Turn the ignition key on and observe that the LED on the Security Relearn Tool is flashing green/blue, which indicates the GEMS has been successfully put into Security Learn Mode. If the LED on the Security Relearn Tool is flashing red there is a communication error. (See below) Check the 5 amp fuse 33 in the engine bay fuse box. Refer to intermittent non-start tab. Treat all the nominated terminals in the BECM, body and engine harness connectors. Please check the Mobi4 connections and go through the instructions again, perhaps several times.
Check that the engine starts when receiving a security code from the Mobi4 and let it run for 5 minutes to set the new code in memory.
Turn the ignition off and unplug the Security Relearn Tool.
Once again, check that the engine starts without receiving a security code from the BECM.
Return the Security Relearn Tool to us at your own cost with tracking and covered by insurance for AU$200.00.
*After satisfactory testing and inspection (for un-contamination), a full refund of your $200.00 deposit will be made to you. Before you order - Check the diagnostic socket in your vehicle for any signs of moisture or corrosion. Use a mirror and torch (flash light) to illuminate the socket and visually inspect it. If there are any signs of water or corrosion, please order and fit a Data replacement diagnostic connector. Connecting the plug of the Security Relearn Tool to a contaminated diagnostic socket will contaminate its plug and require, on its return to us, cleaning (or replacement if water has penetrated inside) at an additional cost, as we do not want to send out a dead tool or to contaminate the diagnostic socket in another vehicle. Refer to DATA.
BECM did not respond to a wake up.
BECM communication failure.
BECM is in alarm or immobilised. Turn off alarm and mobilise.
BECM write failure.
GEMS wake up failure.
GEMS start diagnostic failure.
GEMS security failure.
GEMS did not enter Security Learn Mode.
Note: I have had one GEMS unit that would not go into Security Relearn and I have had reports of only a very few others.
If you cannot get the GEMS into Security Learn Mode and your BECM is not in alarm or immobilised please remove the GEMS unit (Remove and Refit tab) and send it to us together with the Mobi4 and Security Relearn Tool and we will attempt to do a Reprogram on the test bench in our workshop.
Remove & Refit
Turn the ignition key off. The battery does not have to be disconnected, as after about 20 seconds, there is no power in the GEMS box with the ignition key off.
These instructions are for the P-38 Range Rover – other vehicles will have their GEMS in a different location.
Access the engine bay.
Loosen the screws at each end of the long, narrow, black cover behind the battery and remove the cover. Check the sealing gasket for re-usability.
In turn, depress the release latch on the side of each of the three GEMS connectors and wiggle the connectors off the top of the GEMS unit.
Start with the large black, then the red and the small black one last. (It may be a bit of a struggle, as they will not want to come off – but it can be done!)
With all three connectors removed, slide the GEMS up and out of the box. Return the anti-rattle clamp into the black box if it was also removed with the GEMS unit.
Cut and place a couple of layers of corrugated cardboard over the three connectors on the side of the GEMS unit, wrap the lot in bubble wrap and send it for re-programming.
Refit the returned GEMS unit to the black box in the engine bay.
Refit the three connectors.
There is now one wire to cut and insulate. In the RED connector there is a BLACK wire in the chamber that is second from the end (next to the larger BLACK connector).
Cut the BLACK wire a short distance from the connector (in the event that it has to be re-attached).
Fold each of the ends of the BLACK wire back over itself to form a J and slip one of the two supplied insulating sleeves over each of the two ends.
Below is the Image for the same.
There are problems with the electrical integrity of the gold plated terminals of signal wires between the BECM and the GEMS as corrosion is developing between the gold plating and the base metal of the terminal’s body. Disconnection and reconnection may temporarily cure the problem, as the physical act seems to displace some of the insulating corrosion for a short time. However, the only permanent solution that has been found is to put a very, very small amount of a contact treatment solution on these gold terminals. We have been doing this for years on these gold terminals (and the connectors under the seats for seatbelt pretensioners - among others) and have not had any further problems. Use only contact treatment solutions that are made for gold contacts. Jaycar stores carry a Deoxit ProGold product or you can try a local electronics store for a contact treatment solution that is used on the gold connectors of audio/visual equipment.
Terminals to treat
Pin 5 of the 16-pin green connector (C-112) on the front of the BECM has a black wire sending the coded bit stream to pin 26 of the 36-pin red connector of the GEMS through pin 1 of the body/engine harness connector.
Pin 22 of the 36-pin black connector on the GEMS has a black wire with a yellow trace that sends the OK signal back to pin 5 of the 20-pin green connector (C-114) on the front of the BECM through pin 4 of the body/engine harness connector.
The body/engine harness connector is located in the engine bay under the coolant expansion tank.
Normal immobilization system operation
When the ignition is switched on, the Body Electronic Control Module (BECM) continuously sends a coded bit stream to the Generic Engine Management System (GEMS) until it accepts the code as valid, at which time GEMS returns an OK signal to the BECM.
The BECM illuminates the Check Engine lamp, stops sending the coded bit stream, enables the starter relay and allows the engine to crank over when the key is turned to the start position.
In order for the engine to start and run, the GEMS enables the ignition and injection.
When the BECM is in alarm or immobilized
The BECM does not send the coded bit stream. The GEMS, not having received a code, will neither inject fuel nor activate the ignition system. The BECM, not having received the OK signal from GEMS, will not turn on the Check Engine lamp or allow the engine to crank over.