Mobi-Lize


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MOBI-LIZE bypasses the troublesome immobilisation system on vehicles using the GEMS engine management system (P38 Range Rover, etc). The engine can be started and will run even if the BECM is in alarm, dead or even removed from the vehicle.

Normal immobilisation system operation

When the ignition is switched on, the BECM continuously sends a coded bit stream to the GEMS until the GEMS accepts the code as valid. The GEMS then returns a signal to the BECM at which time the BECM stops sending the coded bit stream and illuminates the Check Engine lamp. The BECM will then enable the starter relay and allow the engine to crank. The GEMS will enable the ignition and injection to start the engine. When the BECM is in alarm or immobilised the BECM does not send the coded bit stream to the GEMS. The GEMS not having received a valid code will neither inject fuel nor operate the ignition system. The BECM not having received the code accepted signal from GEMS does not allow the engine to crank.

MOBI-LIZE operation

After the GEMS has been introduced to the MOB-LIZE with a security code re-learn the MOBI-LIZE sends a coded bit stream directly to the GEMS regardless of what state the BECM is in. When the code has been accepted the GEMS returns a signal to both the MOBI-LIZE and the BECM the MOBI-LIZE stops sending the coded bit stream. Under normal circumstances the BECM will then allow the engine to be cranked over and started. In other circumstances (in alarm or dead) either bypassing the starter relay or the BECM starting circuits is required to initiate the cranking of the engine. Details for doing this are included in the MOBI-LIZE fitting instructions.


MOBI-LIZE – Fitting Instructions

MOBI-LIZE bypasses the troublesome immobilisation system on vehicles using the GEMS engine management system (P38 Range Rover, etc). The engine can be started and will run even if the BECM is in alarm, dead or even removed from the vehicle.

MOBI-LIZE operation

After the GEMS has been introduced to the MOB-LIZE with a security code re-learn the MOBI-LIZE sends a coded bit stream directly to the GEMS regardless of what state the BECM is in. When the code has been accepted the GEMS returns a signal to both the MOBI-LIZE and the BECM the MOBI-LIZE stops sending the coded bit stream. Under normal circumstances the BECM will then allow the engine to be cranked over and started. In other circumstances (in alarm or dead) either bypassing the starter relay or the BECM starting circuits is required to initiate the cranking of the engine. Details for doing this are included in the MOBI-LIZE fitting instructions below.

Connecting MOBI-LIZE

You can connect the MOBI-LIZE into the wiring on top of the GEMS or at the BECM.

On top of the GEMS in the engine bay there could possibly be an issue with the higher temperatures encountered on a hot restart. Feedback please! MOBI-LIZE is manufactured with the highest temperature components that I can source here in Australia and I have not heard of any temperature related problems. That said the front of the BECM is a much cooler environment. 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 MOBI-LIZE may not reach the GEMS. See 'intermittent non-start' at the end.

1. Power – ignition on. This operation requires connection to a source of power that is available both with the ignition switched on and during cranking. This connection is made using the white wire from the MOBI-LIZE.
GEMS - Solder the white wire to the large brown wire with the orange trace going to the 18-pin black connector at the end of the ECM (pin 7).
BECM – Solder the short white wire to the white wire with the purple trace from pin 1 of the 12 pin grey connector on the front of the BECM (through fuse 6). Refer to the attached BECM drawing.

2. Earth – This operation requires the connection of the short black wire from the MOBI-LIZE.
GEMS - Solder the short black wire to any one of the four black wires going to the 18-pin black connector at the end of the GEMS (pins 5, 9, 10 or 16).
BECM – Extend the short black wire to the outside rear corner and solder to the large black earth wire to the BECM.

3. Security code sending – bit stream. This operation requires that the black wire between the BECM and the GEMS be cut, as the original bit stream from the BECM is no longer used. The black wire going to the GEMS is soldered to the long black (bit stream out) wire from the MOBI-LIZE and the connection insulated. The unused black bit stream wire from the BECM is tied back and insulated.
GEMS ECM - Pin 26 of the 36-pin red connector of the ECM has a black wire receiving the bit stream.
BECM – Pin 5 of the 16-pin green connector on the front of the BECM has a black wire sending out the bit stream.

4. Code accepted – MIL This operation requires the connection of the yellow wire with the black trace from the MOBI-LIZE to the black wire with the yellow trace between the GEMS and the BECM.
GEMS - Pin 22 of the 36-pin black connector on the GEMS has a black wire with a yellow trace that sends out the MIL signal.
BECM – pin 5 of the 20-pin green connector on the front of the BECM

You will now have to do a Security Re-learn to the GEMS so it can learn the new security code that is being sent from the MOBI-LIZE. Please note: I have had one GEMS that would not do a security relearn. It was on a 95MY. There have been other reported cases - feedback please.

By-pass a dead BECM To switch on the Ignition ON Relay you will need to bridge the white wire on pin 8 of the 10 pin white connector on the rear of the BECM to the white wire on pin 9 of the 14 pin yellow connector on the front of the BECM. When the ignition switch is turned to the Ignition ON position the switched earth signal goes around the dead BECM to operate the Ignition ON Relay in the engine bay fuse box.
To switch on the Starter Relay you will need to bridge the white wire with the red trace on pin 6 of the 20 pin yellow connector on the side of the BECM under the fuses to the white wire with the red trace on pin 2 of the 10 pin yellow connector on the front of the BECM. When the ignition switch is turned to the Start position the switched earth signal goes around the dead BECM to operate the Start Relay in the engine bay fuse box.

You could, of course, pre-install the wires to do the above by-pass operations with connectors or switches so that if or when trouble strikes you are prepared.

Intermittent non-start due to engine immobilisation

We are having much ado about the electrical integrity of the gold plated terminals used between the BECM and the ECM. These terminals, which are used for signals, only handle very low powers levels and are therefore susceptible to corrosion occurring between the gold plating and the base metal of the terminal’s body. Disturbing them by disconnection and reconnection may temporarily cure the problem as the physical act seems to displace the insulating corrosion however the only permanent solution that we have found is to put a very, very small amount of a contact treatment solution on the 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.

Try the electronics stores in your area for the contact treatment solution that is used on the gold connectors for audio/visual equipment.

Terminals to treat

GEMS Pin 5 of the 16-pin green connector 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 MIL signal back to pin 5 of the 20-pin green connector 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.

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