I've got an immobolizer alarm in the R and I have a feeling it's busted. Over the last few months I've been having some trouble with it and so far I've had to bypass the starter kill.

One day it's working and the next day the car won't start. I'm trying to rule out some other possibilities, like the main relay.

To rule this out I need to find out what fails with the main relay.

Here's what works and doesn't when you turn on the ignition:

Radio & Antenna - ON
Dash - ALL OFF
Dash Clock - OFF
Interior Lights - ON
Exterior Lights - ON
Fuel - I think OFF (don't smell after cranking)
ECM - ?

Thanks for your help guys! Looks like I have to tow it to someone that is familiar with my alarm and get a new one put in.

 

if the main relay is bad it won't start because no power to turn on the fuel pump.

 

Are the alarm wire connections solidered or fastened well? Are all of the factory plugs under the dash connected securely? Sounds like a loose or broken connection.

 

Main relay and ECU activation is fairly easy to test by listening to the fuel pump. It will prime for exactly 2 seconds as soon as you turn the key to "ON." You can also look for voltage across the 2 fuel pump wires under the rear seat during the same 2-second interval + cranking. But why do you think it's the main relay?

This is what I'd do for now:
1. Locate and bypass the fuel cut-off relay if you have one (you implied that you do). If you can't find it with ease, you might consider looking at the alarm wiring diagram and tracing any trigger wires, similar to the starter kill you've already bypassed.
2. See what the hell is up with your dash lights. This might be related to a bigger dash harness or grounding problem, not the alarm itself.

Are you the first owner?

 

I highly doubt that it's the main relay... main relays should last at least 175K miles... unless you have surpassed this kind of mileage...

 

Thanks for your support guys, I don't think it's the main relay either, since it typically only fails after it has been heated up, and works again for a while once it's allowed to cool down.

I'm the first owner of the alarm, but second on the car. I agree its likely a bad connection, but hopefully not on the car side. I'm currently working with the alarm manufacturer on bypassing the security. The specialized shop that installed it in my home town closed down unfortunately.

 

I asked if you were the owner because there exists a distinct possibility that the previous owner installed a fuel cut-off switch (or similar). This switch may have been bypassed before the sale, and it is this connection which may be the cause of your problems.

 

That almost sounds like a dying ignitor in the distributor. I don't know much about alarm wiring though. Good luck.

 

Main relays typically dont last 60,000 miles in many cases, can last forever in other cases. Nobody mentioned that there are actually two relays inside of the main relay assy. The second relay is for the fuel injectors, BUT if the fuel pump is priming then the injector relay is probably good because it also powers up a portion of the ECM but this does not mean that the injectors are getting power. See if the injectors are getting 12 volts too anytime the key is turned on with your multimeter.

Dont forget that you just may be having other non related problems to the main relay, just simply no start troubles which have a long list of issues, check for spark, fuel, timing, compression, then injection, mechanical timing, spark tester = high KV (not just your spark plug outside of the cylinder = low KV), fuel pressure and volumn, trouble codes in the ECM, etc.

 

Thanks again for the great ideas.

OK so I got tech support on the line, took apart the security system last night and bypassed the immobolizer circuits. Voila the car started. So the alarm died.

Sucks I had to spend money on a new one, but hey what can you do, it's mandatory for our cars.