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Immobiliser and Fuel cut solenoid


Well-Known Member
Dec 11, 2010
I have a late model 80 with factory TVSS alarm immobiliser. I recently needed to troubleshoot the fuel cut solenoid, but found that I couldn't see it as it was under a cover. I suspect this is a physical protection for the immobiliser function. (edit: immobiliser is factory and separate to TVSS alarm; the alarm just makes noise and operates the door locks but does nothing to stop the car being driven)

Has anyone tried removing and reinstalling the cover in place, and if so how? Appreciate it may be better to PM the information.


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Strange to see a Bosch part on a Denso pump....
I wonder if this was a dealer/importer fit ?
That cover is present on mine although it's not shown in the FSM.
The TVSS and immobiliser are completely separate. The immobiliser was factory fitted and the TVSS isn't but was fitted by Toyota GB.
The immobiliser was factory fitted and the TVSS isn't but was fitted by Toyota GB.

Yup, appears so. Here is the Toyota GB guide on how to fit TVSS. TOYOTA TVSS IIIB INSTALLATION INSTRUCTIONS MANUAL Pdf Download - [Leaving Land Cruiser Club]


2 and 5 are on by default, which relates to (via a Celica manual{4CD304D2-A41B-91D3-284C-8CC4FE5FA41B}/Celica_TVSSIIIB.pdf)


So '4 off 5 on' is Valet mode, which I'm trying to get the definition for... (edit: )


Just ensuring that the fuel cut solenoid is in no way connected to the TVSS, which switch 3 made me pause for thought as maybe in diesels it runs to the fuel cut. However I believe they are indeed separate as I've driven the car with the alarm going off before.


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So fairly sure it's to do with T22 Transponder Key Computer via Pin 10. Pin 11 to the ECU appears to only apply to Petrols (*12).

And the only input the fuel cut valve gets (which I think is the name for the armoured thing) comes from the Transponder.
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These Bosch units seem to be called a similar thing 'BOSCH ANTI-THEFT SOLENOID CONTROL VALVE'

So is it just a dumb voltage wire to a solenoid or what?
Salvage units appear to have some circuit under this cover. I'm betting the signal from the transponder computer is binary to this item, which then decides to pass voltage to the solenoid it is hiding. Otherwise you'd just be able to tap one of the three wires to get it to start which would make it pointless.

So, it looks like taking the unit off to expose the solenoid (likely requiring the pump taking off) or 'modifying' the circuit is necessary. Fiat Ducato 2.8jtd (2003) intermittent key recognition and starting. - [Leaving Land Cruiser Club]

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So after all that, if your 1996 diesel is cranking but refusing to start, it's almost certainly the transponder immobiliser either not reading the chip or some power gremlin to that system.

If the solenoid was then revealed by removing this Bosch cover, one would still need to think how to rewire the signal. In theory it looks like pin 2 in the middle would run to the solenoid as the +ve from IG2.

Here ends my TED talk.
Appendix: if you got here because you've no keys that can make the transponder ECU work, instead of removing the system, find a better locksmith familiar with transponder chips and their documented flaws.
Tempting fate here but I've never had trouble with the immobiliser. When I had an extra key cut the dealer had to wipe the immobiliser ECU as it already had 4 keys registered which is the max allowed. Fortunately the key I got with the truck was the master which is needed to wipe/reprogram the ECU.
I replaced the knackered sounder on the TVSS with a used unit from an Avensis of the same era and simply replaced the rechargeable batteries, did a pin out to rearrange the connections in the plug and it's been fine since.