Does this sound like the alternator? FIXED!!!!!

Post by **NafemanNathan** » Fri Oct 30, 2015 9:23 pm

Only just realised you'd asked me a question Merc

The known good one supposedly worked fine bud. Came off Phil's old ATR. What light are you on about though.

Anyway, the search continues, and I have a puzzling situation...

First off, I tried another MAP Sensor (Courtesy of Josh. Cheers fella

). Unfortunately, yet again it didn't make a blind bit of difference

I also tonight disconnected my amp, as a few months ago it blew a fuse (When I hit a pot-hole

). There after the front left speaker buzzes and nothing else (Silence in all other speakers and no music). There are two 20 amp fuses in the amp, the lower one is the one that blew and it continues to blow if I replace it. So for now I've left that particular fuse out and just not bothered with my stereo.

Anyway, I've been thinking for a while that maybe the amp is somehow sapping some power, or there's a bad earth or something. So tonight I decided to disconnect the positive power cable from the battery to the amp (At the battery end). As it's only a temporary thing I went to tuck the bare end of the cable away. Upon doing so it made contact with the chassis and sparked!

I thought hang about, what's going on here? So I stuck the multimeter on the cable and the battery negative and it read 7.55 volts

I then went to the amp end and stuck the multimeter on the amp terminals. That read 7.49 volts

I then out of interest removed the second fuse from the amp (I'm not sure why there's two, what they're for), stuck the multimeter back on the amp terminals and it read 0 volts

The cable at the battery end (obviously still disconnected) read 0 volts then as well, as you would expect.

This is the amp with the blowing fuse removed but showing the one I've just removed tonight...

And just the disconnected cable, battery end...

Now with both 20 amp fuses removed the car is still struggling when all the electrical items are on, but that whole thing with the cable having 7.55/7.49 volts is very odd right?...

Any ideas?...

mercutio · Post by **mercutio** » Fri Oct 30, 2015 9:26 pm

dont some amps have caps? and i dont mean your Yorkshire variety

i meant the battery light was the alternator charging? was the battery light on?

Post by **NafemanNathan** » Fri Oct 30, 2015 9:31 pm

Caps? ... Yorkshire?

And no, the battery lights never been on (Apart from at ignition).

mercutio · Post by **mercutio** » Fri Oct 30, 2015 9:43 pm

caps = capacitor so will hold some charge if it has one

so the Alternator was charging and the battery light was off?

Post by **NafemanNathan** » Fri Oct 30, 2015 9:49 pm

Ahh ok. Doesn't 7 odd volts sound quite high though?

And yes, both alternators were charging with no battery light on.

mercutio · Post by **mercutio** » Fri Oct 30, 2015 9:56 pm

NafemanNathan wrote:Ahh ok. Doesn't 7 odd volts sound quite high though?

dont know i know very little about ICE i think Robs your man there

NafemanNathan wrote:And yes, both alternators were charging with no battery light on.

so they are charging just not enough??

Post by **NafemanNathan** » Fri Oct 30, 2015 10:22 pm

mercutio wrote:
NafemanNathan wrote:And yes, both alternators were charging with no battery light on.
so they are charging just not enough??

The "corrections" aren't being made when things like main-beam, full-beam, fog-lights, rear demister, air-con are turned on, and when PAS is activated. The revs drop to around 400-500rpm. If I accelerate to say 3000rpm and then let my foot off, the revs will drop even lower and then level out again at 400/500rpm. Braking has a similar effect.

I've just been reading this (About a quarter of the way through)...

http://ecomodder.com/forum/showthread.p ... d-967.html

And this bit...

The main output device that controls engine idle is the idle air control (IAC) valve. This valve was added to all models in 1988 and is controlled by at least the following inputs:

Air Conditioning Switch
Brake Light Switch
Clutch Switch (Manual Transmissions)
Electric Load Detector (ELD)
Engine Coolant Temp (ECT) Sensor
Engine RPM
Gear Position Switch (Automatics)
Power Steering Pressure (PSP) Switch
Starter Signal Input

... Now makes me think it's the IACV, as everything listed above has an effect. Even dipping the clutch has a very subtle impact.

Do our cars have ELDs (Electrical Load Detectors)?

Post by **RattyMcClelland** » Sat Oct 31, 2015 12:07 am

Amps can hold residual charge in the power capacitor for a short amount of time after turning the car off. 2 fuses for the 2 power packs inside if its got 2 power supplies inside like a 4 channel amp.

Post by **NafemanNathan** » Sat Oct 31, 2015 12:18 am

Thanks for that Ratty. At least it makes sense now. Cheers Merc

89 UKDM BA4 4WS (resto job!) · Post by **wurlycorner** » Sat Oct 31, 2015 7:20 am

What has been said about the caps is correct, but after touching the positive to earth though, there shouldn't be any residual left - the capacitors in an amp like that aren't very big really, so they wouldnt be able to still hold charge that long...
Sounds like something odd going on.

Sounds like the remote feed might be staying live and leaking across into the main live of the amp?
I'd suggest take the amp apart, there may be something come loose inside, bridging across some terminals or pins on the board.
Also check that the 'remote' has been properly connected back to the stereo remote output, instead of spliced into something else inside the car.
With the main amp positive lead disconnected at the battery and the stereo turned off, the remote (well, all of the amp) should be completely dead - no feed going to it. If you still have voltage on the remote (or any of the amp terminals) then someone has bodged the install, or some wiring insulation is breaking down in the car (or you have a massive inductor somewhere

)