are you sitting comfortably? then i'll begin.....
Day 1… you better get comfy and grab a cuppa! Oh, and take notes, I may ask questions later…
After having a play on the car at the weekend, an unusual fault reared its head on Monday on the way to work…. As I was on my travels I noticed the engine hatch and boot warning lights were flickering. So I got to work and had a quick check, unplugging the engine hatch warning switch and checking the dash… the light was still on, along with the boot lamp, which was definitely closed!
Very odd! So I had to wait until I got home before I could investigate further.
As I’d been playing inside the car, everything that I had moved was moved again, and double checked any wires that may have been caught/damaged… they hadn’t but something had happened somewhere!
Tapping the top of the dash above the instruments made the lights flicker, so was it a rogue wire/ solder blob/relic of the instrument ring mod? So the dash was removed to check that the instruments were fine. They were, but while it was out I checked the wire connectors, checking if there was a short to earth on the signal wires coming into the gauge cluster….Hmmm both the signal wires shorted to earth… so the instrument cluster wasn’t to blame! Whats next….? Apart from putting the dash back together!
Moving to the back, I opened the boot to check the boot switch, using a screwdriver to activate the latch mechanism, noting that the boot light stayed illuminated all the time! Something up there… so the lock mechanism removed, checked, microswitch mechanical and electrical function checked-out ok, so was reassembled! Not that then!
Checked the wiring going to the switch, 3 wires, one from the boot light, one to earth, and another signal wire disappearing into the loom, presumably for the security system. Disconnecting this third wire resulted in the dash light behaving as it should and the boot light going out when it should!! But I still had the engine hatch light shining brightly! By now it was getting late so everything was buttoned back together for driving in the morning…..
Day 2!
Driving to work, engine hatch light still firmly on, boot light out as the signal wire is disconnected! This made me think it must be something with the security system(s) on the car… Although the wires for the 2 lights travel down the same loom, the chances of just those 2 wires shorting to earth and no other circuits being affected are very remote… so it must be something that needs to know if the door/boot/hatch are open/closed. So lunch time was spent pulling the glove box and associated covers to gain access to all the wires that hide behind there (the original idea was to unplug the side loom from the main loom and isolate the short a little further.)
When i got back home I tracked down the factory security controller (different in configuration and location to the one in the manual just to be awkward!) and found the wires that the aftermarket alarm fitters had tapped into when the alarm was fitted way before I got the car! What a lovely job they made! Well, nearly! I found the hatch and boot wires, both attacked by the alarm fitters, so checked the continuity to earth, and a short was there… so was it the alarm? Disconnected the alarm box, checked the wires… still shorted! So snipped the ‘alarm addition’ wires and checked the dash function….
The hatch lights and boot lights work as they should! Hurrah! I say as they ‘should’, as I’ve only every seen them both come on at the same time, open the boot, both lights, open the hatch, both lights. I thought it was just 1 light with a black bar across it! Who knew! Then again I thought the ‘brake light failure‘ warning lamp was an optional extra until I found mine had black tape over it, from when the inside brake lights were tweaked to be fog lamps when it was imported!
So the alarm wiring had basically shorted these 2 circuits together, tying their function together!
The alarm wire causing the problem was shorted to earth, so checking the alarm was disconnected and it was still shorted to earth, it must be shorted somewhere along it’s line. I traced it thru the bulkhead, and assumed it must go to the bonnet switch…. Better open the bonnet then….. Pulling the bonnet release, and no weight on it…. No click, no bonnet popping up… hmmmm bum, has the cable broken… so I pop the headlights, and pull the lever as my dad lifts the bonnet up… phew it opens, and the cable is moving at the latch end no problem!
We ran a new cable through to the bonnet switch, presuming it was chaiffed somewhere, causing the short to earth. simply soldered a new wire to the end of the old and pulled it through! Looking at it, it wasn’t damaged anyway. It was something far more subtle!
So when I was playing before this all started, I removed the sill cover/edge finisher (the one that goes behind the bonnet pull) so had released the bonnet to get the panel off . As it hadn’t ‘popped’ I’d forgotten about it, it looked closed, but the bonnet had lifted barely 1mm, just enough to lift the bonnet to let the bonnet switch close its circuit to earth when the car vibrated over the bumps, and just enough to rattle when I slapped the top of the dash (only when I slapped the drivers side though, the lights didn’t flicker when I did the same on the passenger side!!!!) hence why I thought it was instrument based!
So the way the alarm had been wired, the bonnet switch illuminated the boot/hatch warning lights, much the same as happens when either the boot or hatch is opened! As I’d never been in the car with the bonnet open and ignition on, I’d never seen it! It also turns out the bonnet being lifted turned on the boot light! Replacing the cut alarm wires with the addition of a couple of diodes meant the correct lamp function was restored but with the alarm function unaffected!
So why didn’t the bonnet pop…. That was for day 3!
Day 3…
The task of the day was to pull the bonnet catch off the car and see whats wrong… before I took the catch off, I marked its position so I could put it back in the same place, and took out the 3 bolts. Disconnected the cable pull, and had a look…. Oh dear...
I think it’s pretty obvious why the bonnet has lost it’s pop-up capability..
Strange that just this corner had corroded, as the rest is fine! The spring mount is just about there….
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Originally Posted by PeterW
