500 SEC(C126) with Cobra Alarm & Immobiliser - Location

[tristand]

Hi, I recently bought a 1992 500 SEC. It has a Cobra 7928 system consisting of 7925 and 1984. I'm assuming the 1984 is the immobiliser. I need to get a key for, for the pin I need the serial number of the immobiliser.

Would anyone know where installers would have typically placed the immobiliser unit?

 

[alabbasi]

No, if people knew where they modules were hidden it would defeat the purpose. If there's a key that goes into a slot on the dash, you will need to trace that wire from the slot to the immobilizer, Any electrician worth his salt will find it in 10 minutes.

 

[tristand]

The Cobra 7928 setup is a complex one, with an alarm unit and an immobiliser unit. It spreads its tentacles throughout the car and tracing the LED wire or the touchkey receptacle wire will only bring you back to the alarm unit. You can see from the attached wiring diagram that only one signal wire runs between the Alarm unit and the immobiliser. With the wiring loom for the system tightly bound together and well sealed, it makes it challenging to locate the immobiliser.

 

[grober]

Typically the alarm control unit was located up behind the dash facia or in the passenger footwell [footplate/ side kick plate ]or behind the boot liners.

 

[tristand]

Typically the alarm control unit was located up behind the dash facia or in the passenger footwell [footplate/ side kick plate ]or behind the boot liners.

I have found the location, but not going to disclose it on the forum. If anyone wants to find the likely location for the SEC, please IM me. It was a UK install so probably a standard set. Not that many of these cars are still sitting on the street waiting to be "boosted", but just in case.

I've decided to keep the alarm and immobiliser in place with the hope to keep it operational. I've ordered a new keyfob and requested the PIN. If that doesn't work, I'll need to start the task of removing this thing(which was probably necessary in the early 90s). The installation is shocking, cut wires, twisted together and covered using insulating tape.

 

[grober]

Typically these alarms were a supplying MB dealer fit predelivery and of variable quality depending on who did it. My advice would be to remove the major components assuming the alarm is currently disabled. You need not remove all the wiring but reinstate the original factory wiring links broken by the immobiliser circuits. The reason I suggest this is to prevent any unwanted in immobilisations leaving you stranded. in the future due to poor wiring. If you feel you need added security get an new alarm system fitted by competent vehicle electrician.