scoobyster

Hi All,

I have just completed a full cambelt service which took me rather longer than expected. I renewed all the idler pulleys, tensioner, waterpump, etc since I'm coming up for 100k miles so it seemed wise. I also removed the oil pump to secure the loose screws from the back plate. The tensioner pulley fixing thread came out with the bolt so I had to mess around with a helicoil, which meant taking the bumper off for sufficient access, which meant I found rust at the bumper mount, decided to fix that, etc. All in all it took a lot of faffing and a couple of months off the road while I did it bit by bit at the weekends.

I neglected the battery in the first month or so of this, forgetting to put it on charge. My (supposedly intelligent) charger/conditioner claimed to have revived this to a full charge, but upon trying to build oil pressure prior to starting after reassembly - it wouldn't turn the engine over, even with plugs removed. It was 10 years old and been weak for a while, so fair enough. I borrowed the battery from my other car and primed the oil pump etc with this no problem. I had the crank position sensor unplugged as well as the spark plugs removed for this. I then bought a replacement battery, charged it up and fitted to the car ready for actual starting. Obviously the ECU will have been reset by all this battery changing. At this stage I had refitted the plugs and leads but left the crank position sensor unplugged. I wanted to build up oil pressure again before the final start, but the engine unexpectedly started (with just the usual ECU-just-reset bit of lumpyness) with the CPS unplugged. I pulled the car out of the garage like this and allowed it to warm up a bit on the drive, before shutting off to plug in the CPS. I noticed the battery not charging warning light was on during this period of idling (probably was from the start, but I was too phased by it starting when it shouldn't so I didn't notice).

I shut off the engine, plugged the crank position sensor back in and restarted, but still the charge warning light was on. I took it for a short drive to warm it up properly at this stage and noticed that the brake fluid low warning light was also on (previously mistook this for the handbrake light). The brake fluid is not low, the float switch is floating as it should, and I haven't knowingly touched this area during the cambelt work.

I have moved the alternator about a fair bit during the work, so it's possible I've damaged the wiring or a plug has become dislodged. To be honest I had struggled to unplug it so had just moved it out of the way whilst still wired in. I have fitted a new alternator belt and it's adjusted properly etc. I will test whether the alternator is actually providing voltage to the battery tonight. I suspect it may be as the headlights dimmed when the engine revs dipped very low while idling when the ECU was still learning its settings, which to me suggests the alternator was helping out (and running the bulbs on ~14v) at higher revs, allowing them to dim on battery only at the very low revs, unless an almost-stalled condition provokes the ECU to provide more power to the plugs or something? My battery conditioner did suggest the battery needed charging upon parking up though.

Anyway that's a long way to go about saying I have an erroneous brake fluid level light, and suspected erroneous charge error light. Any suggestions what could cause these, perhaps in tandem. Could the allowing to start with missing crank position sensor be related, or is that because of starting with a newly reset ECU? Car is a MY95 Impreza, non-turbo.

Cheers.

scoobyster

Quick update. With engine off I've got 13.15v on the +ve terminal on the alternator, exactly the same as at the battery. In the two pin plug I've got 8.5v and earth. Does that sound about right? If so I presume the wiring is good. I didn't start it up to check the charging voltage as the weather is filthy, so I'll do that tomorrow.

One last thought is that the new battery is a Halfords Advanced 'Calcium' one. I read somewhere that older cars (or was it chargers?) can have difficulty in charging these - could this be the problem?

scoobyster

Right, started her up this morning. Battery voltage before start: 12.8v, after starting: 15.2v, after 7 mile journey (and engine shut off): 13.4v. Clearly the alternator is working and charging the battery, but the charge light is on regardless. Is the 15.2v too much and therefore why the light is on? Perhaps the calcium battery has too low an internal resistance or something along those lines? Could excess voltage in the +12v live circuits also cause the brake fluid warning light? Seems implausible but who knows. I will borrow my MX5's battery again when I get home and see if starting with that gives the same fault(s), though that is an AGM/gel battery so a bit odd ball as well.

scoobyster

Any ideas folks?

I swapped the new battery for the old one (known good with the car's charging system, just goosed). It needed a bump start with that but then ran ok with 15.2v (again) showing across the battery when running. Seem the calcium battery theory is out, shame as I was rather relying on it!

I'm now pretty convinced the charging circuit is fine, though there is the possibility it's warning me about over-charging, how can I check for that? Is 15.2v typical? It does seem high to me. If that is ok though, it seems I have two erroneous dash lights, but no clue what the check next!

scoobyster

In case anyone is out there... My alternator light woes continue.

Turns out it is common to get the charge light and brake light on together, the two are a sort of pair in the instrument cluster, connected with a diode so they will light together in some circumstances.

I've tried with a 3rd battery and the lights are still on and it's still over charging so that theory is definitely out.

I took the alternator to a local repair man who tested it by spinning up on a bench and said it's fine. He suggested it would be the fuse to the sensor wire on the alternator. I don't think there is such a fuse - the regulator plug has two wires - white (thick) and black/white (thin). With the engine off the white one shows between 5 and 8v. The black/white one connects to earth but with 20Ohm of resistance, so I think this is going to the dash warning light.

I've found a wiring diagram http://ken-gilbert.com/wrx/mans/pre97/WiringDiag.pdf
This suggests that the white wire on the alternator(/generator) should be connected straight to the battery, as per the main power feed from the alternator itself (see page 2, 15, 16). My multimeter however says that there is no continuity between that white wire and the battery +ve (there is on the two to the main alternator power output - 0.5ohm resistance).

I guess the wiring diagram isn't quite right for my car and there must be something between the battery and the alternator sensor plug. The wire can't have broken as there is some voltage getting through. I suspect the alternator 'thinks' the battery is at a very low voltage (5 - 8v) so is charging for all it's worth, but still not 'seeing' the battery voltage come up, hence lighting the warning light.

I'm trying to trace the white wire itself but it's not easy, especially as it runs in parallel with two identical wires. Only those two end up in the main fuse box however.

Any suggestions would be most welcome. I guess I've just got to continue until I find what's getting in the way in this white wire. If someone can confirm I've got the right end of the stick in my interpretation of the problem and the wiring diagram, that would be very helpful.

Deadslow

iTrader: (1)

Thread resurrectiion but...

Did you ever get to the bottom of this? I have the same problem. Put a new battery in and suddenly the lights won't go out.

Would resetting the ECU do any good?