FFG

FFG

Active Member
Getting some niggles sorted on the S3 for the MoT on Friday. Came to start it yesterday and there are no lights on when the ignition is on. I recall the oil pressure light being on but can't recall if anything else should be on. Fuel gauge works and it does start but would like to get the warning lights working. Any ideas on what it might be or where the lights are fed from - its all a bit tight behind the dash.
FFG
 
Thanks. So ignition light and oil pressure light should be on. Neither are on so I guess the 2 are on the same circuit. Any ideas what it could be or where to start?
 
Ignition lamp and oil pressure lamp should be on with ignition and go out when engine starts. But lack of either is not an MOT fail.
 
Understand it won't fail the MoT on that but would like to get them working anyway. More concerned about emissions as its got a P6 V8 and its running rich - will be pretty obvious in an enclosed space.
 
The ignition light is wired between the alternator and fuse a fuse under the steering column. The oil light is wired to a different fuse and the oil pressure switch. Have you looked behind the dash to make sure the lights are connected and in their holders. If the ignition light isn't working the alternator won't be charging.

Col
 
Thanks. I'll check. I've checked all the fuses in the fuse box and all are OK. Seems to coincidental they are both stop working.
 
Yes agreed. That's why I would look behind the dash. It's easier to see with the steering wheel removed. If it's got oil in it I wouldn't be too worried about the oil light but the alternator needs the ignition light circuit to work. Could just be a couple of dud bulbs. When I got my landy, all the dash bulbs were dead. I suppose they had blown one by one and previous owners didn't bother to replace them.

Col
 
They were working so the bulbs were OK, but will check. From what I can see there should be a brown/yellow from alternator to the ignition light and a white feed from the fuse box to the ignition light. Will check the bulb first and then these 2 wires. Defo need the light working if it's not charging the battery. Oil if full as I check it regularly due to a sump weep which I'll fix soon.
 
Landy wiring is a Pandora's box but in my experience most things turn out to be something simple. It's finding the cause that is the problem. Oil light could just be the wire to the pressure sensor switch has come off. As regards the alternator charging put a volt meter across the battery to see if it reads 14+ volts with engine running.

Col
 
Agreed, but generally its fairly simple and working through it logically I've found I can resolve where the issue is. Done a fair bit of stripping out old redundant wiring and replacing other cable with original colours and the right size cable as many I've replaced looked too weedy. Where is the oil pressure sensor?
 
Try looking near the base of the oil filter for the oil pressure switch. The charge light is wired from the fusebox pre fuse/post ignition switch. There should be volts on the white wire at the bulb when the ignition is on. The brown/white wire goes to the small terminal on the alternator. If the bulb is good then the regulator in the alternator may be faulty - check to see what voltage you have across the battery with the engine running on tickover and revving.
 
The brown and yellow wire goes to the earth side of the charge light bulb on the dash. The white live works as does the bulb if I put an earth to the brown and yelow side of the bulb. The brown and yellow goes into a connector under the bonnet along with 2 other wires but there is no earth at the junction. 2 wires coming out the alternator, a heavy gauge brown and smaller brown only. Does the smaller brown provide the earth? The oil pressure light came on for a short period even though I wasn't doing anything near it which is wierd. Stopped working again now.
 
The 2 other wires going into the connector block at the same point are the 2 indicator warning lamps which both work. I've got the oil pressure warning light working - was just a poor connection in a connector block under the bonnet so as I was messing around with the charge light in the same connector block I was making the connection which is why it was intermittently coming on.
 
Ended up being the lucar on the alternator connector which had been pushed back into the connector block hence not making a connection. Managed to get it forward (tried to get it out but no chance) but it kept going back so did it (I hope) in the end, I tested the voltage before the light worked and it stayed at 12.4 before it was started and when it started. Now the light works its at 14 ish so the light does impact whether the battery is charging, which I was sceptical about. The indicator wires were NOT in the same block - it was just all a bit tight to see.
 
The alternator needs exiting before it begins charging. The bulb is enough to excite/kick start the charging circuit. If you change the bulb for a LED it wont draw enough to begin the process. You have to add a gizmo. Alternatively you can rev its taters off to get the bulb to go out.
 
Its now charging but maybe didn't before but I haven't really used it (only just had a gearbox rebuild as had no 3rd gear) and its been on an accumate regularly. Just need to get the camshaft done now
 
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