Interior light vs ACU?

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Peep110

Member
Posts
51
Location
Oxford
My interior light comes on when you'd expect it to, except when set to (supposedly) being controlled by the door switches via the ACU, where it's on, permanently, unless you flick the switch on the light off.

Fyi there is no circuit board behind the light, just 2 wires and a chassis earth. One of the wires is the 12V feed, the other is the return line to the ACU which is stuck grounded presumably within the ACU.

So my question is: where (physically) is this ACU, and is it common for it to fail to switch the light off? The dash LED works fine btw which proves the door switches are ok too.
 
It’s behind the dash binnacle.
Does your alarm set ok, or do you get a quick beeb beeb when you press the fob button?
 
I'm not sure, pressing the lock button makes a double toot on the horn, pressing the unlock button lights the indicators for a second or two? I don't know, I don't really use it, I have an immobiliser and a SafeTpedal cover plate and that's enough for me as I don't trust car alarms anyway!!
 
Have you got central locking? :confused:
If you’re pressing the immobiliser fob button, you are putting the alarm on too.
A double beep usually indicates a fault. Check your door switch isn’t being kept closed circuit by corrosion inside the door pillar.
 
Sounds like a closed circuit switch. Disconnect them 1 at a time and see which one turns the light off. The double toot on the horn might indicate a low fob battery, I know one of my fobs does the toot and the other doesn't. :)
 
Plump Donkey said:
Sounds like a closed circuit switch. Disconnect them 1 at a time and see which one turns the light off. The double toot on the horn might indicate a low fob battery, I know one of my fobs does the toot and the other doesn't. :)
Click to expand...
It also indicates a door isn't closed properly. ie one of the door switches is still in closed circuit.
 
With all due respect, I said that the dash LED works correctly, i.e. it flashes when the door is shut, lights constantly when the door is open, hence the door switch is ok. These door switches are complete rubbish even when brand new, but mine work. If they were to fail they'd most likely go open circuit due to a loose screw or corrosion, making the system think the door is always shut, which doesn't explain why the light is on. As for central locking, I wish!! I do have a kit for that which I will fit at some point, but it's all in its box right now.
However, if the double beep means there is a fault then that does sound promisingly like it is the ACU which is not behaving itself. Al2O3 you said it's behind the dash binnacle? I will have to go see, probably when I also get round to doing something about those 2 upper stupid plastic tags which are supposed to hold it in place but are broken!
 
Peep110 said:
With all due respect, I said that the dash LED works correctly, i.e. it flashes when the door is shut, lights constantly when the door is open, hence the door switch is ok. These door switches are complete rubbish even when brand new, but mine work. If they were to fail they'd most likely go open circuit due to a loose screw or corrosion, making the system think the door is always shut, which doesn't explain why the light is on. As for central locking, I wish!! I do have a kit for that which I will fit at some point, but it's all in its box right now.
However, if the double beep means there is a fault then that does sound promisingly like it is the ACU which is not behaving itself. Al2O3 you said it's behind the dash binnacle? I will have to go see, probably when I also get round to doing something about those 2 upper stupid plastic tags which are supposed to hold it in place but are broken!
Click to expand...
Never noticed my dash LED doing that :rolleyes:
Still worth checking the function of all the door switches though, including the bonnet switch. You never know your luck and it's a quick thing to do compared to getting at the control unit, which is bolted to the bulkhead behind the dash binnacle, lowish down, but above the height of the rear demister/hazard/fog light switches IIRC.
 
Ok so here's a wierd thing. Conscious of the possibility I'm just being stupid, and having found a schematic which shows that the drivers door switch is not commoned with the others, I just went out to try something. I went, this time, not to the drivers door but to the passenger door, primarily to double/triple check the door switch there and of course the rear ones too. All switches were ok as I'd hoped, but the light remained OFF when I put the light switch to door activated and did not come on for any of those doors. Intrigued I left the light switch set like that and went round to the drivers door and opened it - the light came on!!! I noticed also that the red dash LED was off completely, so I shut the door - the light did not go off and the red LED did not come on, although after a short time the LED did come back on, whereas the light stayed on for a good 6-10mins before eventually switching off.
So, how long should the light stay on for after closing the door? Btw I tried starting the engine, this does not kill the light like in any other car. Is this normal behaviour?
 
Btw apologies Al2O3, I should have said the LEDs behaviour was normal for me, and the fact that it's behaviour changes with the door switch open and shut is a good indicator that it's not stuck, but hey I have nothing to compare it with so who knows?! How does yours behave?
 
Peep110 said:
Btw apologies Al2O3, I should have said the LEDs behaviour was normal for me, and the fact that it's behaviour changes with the door switch open and shut is a good indicator that it's not stuck, but hey I have nothing to compare it with so who knows?! How does yours behave?
Click to expand...
No need to apologise, mate. I've never studied my alarm/immobiliser LED to any great extent and so don't know if there is a link to the door being open or not.

Peep110 said:
Ok so here's a wierd thing. Conscious of the possibility I'm just being stupid, and having found a schematic which shows that the drivers door switch is not commoned with the others, I just went out to try something. I went, this time, not to the drivers door but to the passenger door, primarily to double/triple check the door switch there and of course the rear ones too. All switches were ok as I'd hoped, but the light remained OFF when I put the light switch to door activated and did not come on for any of those doors. Intrigued I left the light switch set like that and went round to the drivers door and opened it - the light came on!!! I noticed also that the red dash LED was off completely, so I shut the door - the light did not go off and the red LED did not come on, although after a short time the LED did come back on, whereas the light stayed on for a good 6-10mins before eventually switching off.
So, how long should the light stay on for after closing the door? Btw I tried starting the engine, this does not kill the light like in any other car. Is this normal behaviour?
Click to expand...
I'm not sure how this is checking the switches. To be sure, IMHO, the best thing to do is to unscrew them from the pillar, check their condition and then test them with a multi-meter.

I think my interior light stays on for about 12 seconds

Pretty sure my LED stays on (can't remember if flashing or solid) when the engine is on. I can check tomorrow for you. Watching El Clasico at the moment :rolleyes::)
 
Ok, my bad .....
Turns out the problem was entirely due to the offside passenger door switch, which was fully functional but just not being pressed in by the strange bracket thing that should have been screwed to the door but which had completely vanished! So, the 6-10min OFF time must be the alarm's default OFF time in the case of a door being left open. Funny enough, after sorting that switch out (i.e. temporarily disabling it until I can fabricate a new bracket or something) I get normal courtesy light operation, so humble apologies to all who quite rightly said it was a switch fault, even though the switch itself was fine :) I guess my confusion was because a) the drivers door still triggered the light, and b) it did eventually go off but not for several minutes. At least I don't have to replace the alarm unit now.
 
Peep110 said:
Ok, my bad .....
Turns out the problem was entirely due to the offside passenger door switch, which was fully functional but just not being pressed in by the strange bracket thing that should have been screwed to the door but which had completely vanished! So, the 6-10min OFF time must be the alarm's default OFF time in the case of a door being left open. Funny enough, after sorting that switch out (i.e. temporarily disabling it until I can fabricate a new bracket or something) I get normal courtesy light operation, so humble apologies to all who quite rightly said it was a switch fault, even though the switch itself was fine :) I guess my confusion was because a) the drivers door still triggered the light, and b) it did eventually go off but not for several minutes. At least I don't have to replace the alarm unit now.
Click to expand...
Pleased you got it sorted. Also, pleased you don't have to take the 10AS box out, cos it's a PITA to get to :)
 
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