[daveo138]

Good evening all.

Having a few issues with the other half's 25, which may or may not be related.

Recently had a few alarm activations for no obvious reason, although it hasn't happened for a few weeks now. Am I right in thinking that it doesn't have volumetric monitoring?

Another problem is the interior light, which sometimes works, sometimes doesn't. This has been the case probably since we've had the car, about six years. It works fine when switched on manually, just not when opening doors, any of them. Then sometimes it will work on the doors.

Another issue is the immobiliser. When we first had the car, I noticed that I could unlock it and it didn't matter how long I left it before trying to start, it would turn over no problem. Having previously had a TF, I knew that it would immobilise if left for only a short time without turning the key, so I expected this to do the same. That issue seems to have righted itself now, but I don't know if all these issues could be related.

I have a Haynes manual for the 25 & ZR, which runs from '99 to '04, although it doesn't seem to cover the later Pektron cars, which this is, so it's not much help.

Any suggestions on where to look for the cause of these problems would be appreciated. Also any pointers as to where I can find a wiring diagram for the later models.

Many thanks

Dave

[Montegoman]

The interior light issue is likely to be the contacts on the door switches. You may have a volumetric alarm. The sensors are at the top of the driver's B pillar. If you lock the doors with the key, rather than the fob, it doesn't activate the volumetric alarm. We have problems in hot weather when we have driven it with the AC on and then park up in the sun. The heat builds up quickly causing air movement and it sets the alarm off. The Pektron system isn't great. The fobs wear out and the proximity to the car to unlock it is ridiculous. We have to hold our remote over the bonnet to activate it sometimes.

[daveo138]

Thanks for the quick reply.

I will check for alarm sensors in the morning.

I don't think the interior light issue is down to door switches, as it either works on all doors, or doesn't work on any of them.

I'm more used to door switches earthing the interior light directly, rather than it being switched by a module somewhere. Cars were much simpler at one time.

[g259fsg]

On the earlier cars like my R8, the interior light is on a timer, it stays on for a short while after the doors are closed, then fades out. This I think is controlled by the Multi-Function Unit. When it's working, does your car do something similar. As you say, on old cars it was a simple on/off push button on the door pillar. The MFU has got electronics and controls other things like intermittent wipers etc., so more to go wrong/intermittent. If you do have something like the MFU, there are usually test routines you can use to check operation.

[Mr Teddy Bear]

It was only the higher spec R8'S that had the timed curtesy light delay; GTI's, GSI's my late 95 SLI has it, but my late 93 [94 model year] 214Si doesn't.

[Montegoman]

It could be a glitch in the MFU. They do come up on Ebay. I have a feeling that the facelift cars have a different MFU to the earlier 25s. I am sure somebody else will be able to confirm. The MFU is under the dash, driver's side. It is easy to replace.

[Roverlike]

Multi Function Unit in case of Pektron alarm equipped cars is replaced by BCU/SCU Pektron box. This box replaces both 5AS and MFU from earlier Rover 25 into one box.

For your problem of alarm going on, I would first check tailgate wiring loom. These are wires that pass through right hand side rubber tube from car body to tailgate. Flaxing wires tend to brake or become bare and touching each other an cause all sorts of problems.

For your interior light problem, I would inspect light unit in the car. It is known that unit have bad contacts after some time of use and it is likely that you have problem on the position when you expect for light to be on after opening the door, while if switched manualy it works.

For the immobiliser as I understand you do not have problem with it?

[daveo138]

For your problem of alarm going on, I would first check tailgate wiring loom. These are wires that pass through right hand side rubber tube from car body to tailgate. Flaxing wires tend to brake or become bare and touching each other an cause all sorts of problems.

Thanks for that.

I found that seven out of the ten wires had insulation damage. Fortunately I saved most of the wiring loom from a 1970s MGB, so I had lots of spare wires of various colours to use for the repair.

The 1970s wiring was much more flexible than 2004!

I tried to attach a photo, but it didn't seem to work.

[daveo138]

You may have a volumetric alarm. The sensors are at the top of the driver's B pillar.

I found the sensors at the top of the B pillar.

I hadn't noticed them before, but I don't drive the car very often.

My wife will sometimes locks the car with the sunroof wide open, but the alarm doesn't go off.

[Roverlike]

My wife will sometimes locks the car with the sunroof wide open, but the alarm doesn't go off.

Your volumetric sensor might fail due to heat over summer.