How To Reset Volvo guard

[paddingtonbear]

Hello
I have a very late 240 with similar grief and was wondering whether the immobiliser might be the same. I have posted on the 240 thread to little avail, except from classic swede. I am also the owner of 2 740 GLEs .......honest :-)

[TonyS9]

Most older immobiliser are basic interuptions on the starter motor trigger, its a simple wiring job to bypass this. Or you can put in an aftermarket alarm fairly easily onto the old alarm loom.

The 1996 on 940 has chip key rfid system that is managed by the fuel computer and needs chips replacing or an older fuel computer to bypass it.

[vickyg]

Sorry for posting in multiple threads but can anyone tell me how to release the immobiliser on 1993 940? Engine turns over good, have unplugged alarmed, removed battery. Still it won't start. No fobs!

[TonyS9]

A 93 has only a starter motor immobiliser, if it's turning over on the starter it's another problem.

[vickyg]

Perhaps a red herring then but the guard LEDs used to blink and now they are on constantly. Which I why I thought immobiliser. I had a Citroen van where the immobiliser went wrong, would always turn over but had to disconnect battery 30 minutes before I could start it. I hoped this 940 problem might be similar. Since the LEDs came on permanently the battery will drain in a couple of days. It's a good battery, only a year old Yuasa and recharges without a problem. I don't know what else on the car could be draining it AND causing non-starting. Or I have two problems suddenly.

[TonyS9]

Originally Posted by vickyg

Perhaps a red herring then but the guard LEDs used to blink and now they are on constantly. Which I why I thought immobiliser. I had a Citroen van where the immobiliser went wrong, would always turn over but had to disconnect battery 30 minutes before I could start it. I hoped this 940 problem might be similar. Since the LEDs came on permanently the battery will drain in a couple of days. It's a good battery, only a year old Yuasa and recharges without a problem. I don't know what else on the car could be draining it AND causing non-starting. Or I have two problems suddenly.

You might have either damaged the alarm with the low voltage running the battery down, or might just have decided its time to die, as I mention in the other thread they don't last much past 20 yrs on several examples I have seen.

You can try resetting the alarm by disconnecting + reconnecting the battery. Do the reconnection very 'positively' don't allow it to arc or fissle by doing it gingerly. This is one of the things that seems to cause it to go in the first place (either in a error state or permanently faulty).

If that doesn't work you just need to remove the alarm module and connect the starter pins. you can google this or I can look it up if necesssary.

[vickyg]

If the starter is controlled by the alarm module then with the alarm module unplugged (I also removed fuses 2 & 5) then it should not turn over? But it does. Or am I missing something?

[TonyS9]

Originally Posted by vickyg

If the starter is controlled by the alarm module then with the alarm module unplugged (I also removed fuses 2 & 5) then it should not turn over? But it does. Or am I missing something?

Indeed you are correct, it must have already been bypassed. And this being a 93 car, the problem must be elsewhere. Unless it has been modified.

The 2 tests you can do to help are
1. check the rpm needle during cranking, it should flicker a little after about 1s (when it should normally start).
2. When you turn the ignition on to the point the light comes on, listen for the pump whining as it primes, before you start cranking. Its quite quiet, so you need a quiet environment, or maybe remove the backseat flap and open the tank access hatch.

After that you need to get into bulb or meter testing.

[Laird Scooby]

Originally Posted by vickyg

If the starter is controlled by the alarm module then with the alarm module unplugged (I also removed fuses 2 & 5) then it should not turn over? But it does. Or am I missing something?

I may be wrong on this bit i have a feeling the Guard II can be bypassed by removing those two fuses. If memory serves, the alarm module controls two relays to prevent starting but with the fuses and/or alarm module removed, there is no control over the relays so they sit there without disconnecting the starter circuit.
I'm not that well up on the Volvo alarm systems having had little to do with them but if you can get it to a driveable state by removing those fuses or the module then it gives you the ability to get the MoT done and worry about the alarm later.

[TonyS9]

Originally Posted by Laird Scooby

I may be wrong on this bit i have a feeling the Guard II can be bypassed by removing those two fuses. If memory serves, the alarm module controls two relays to prevent starting but with the fuses and/or alarm module removed, there is no control over the relays so they sit there without disconnecting the starter circuit.
I'm not that well up on the Volvo alarm systems having had little to do with them but if you can get it to a driveable state by removing those fuses or the module then it gives you the ability to get the MoT done and worry about the alarm later.

In my 95, 97 and 98 cars I have been 'in' the alarm system, the alarm control module is the relay. You have to put a jumper into the socket to bypass it, or just join the wires.

to 95 is guard 1 (seperate RF module on the A pillar, control module under the the steering column attached to the wiring loom)

96-on is guard 2 (bolted under the A piller on the passenger side, behind the glove box and with a seperated RFID key immobiliser system operating with the fuel computer in a Thatcham approved configuration, fuel computer has a security bolt preventing tampering).

Both have the same bypassable starter immobiliser, Guard 2 RFID system cannot be bypassed.

Thats not to say 93 is perhaps different, or its been modified.