What goes click?

[rossdg]

When I lift my foot off the throttle on my 97 2.5D there is a click - about 1 or 2 seconds later (solonoid or vacuum operated switch I'm guessing); when this click occurs my headlights dim slightly and only get back to full brightness when I accelerate again! Any ideas as it's driving me mad......

[missfixit70]

Sounds like you've possibly got alternator issues to me, or someone has really messed about with the wiring? Have you got a leisure battery & if so what is charging it & is it holding charge?

[missfixit70]

May help to fit a voltmeter to be able to monitor what is going on with the LB & SB when this is happening, something like this - http://www.igmaynard.co.uk/bongo/forum/ ... =voltmeter with an on-off-on switch to be able to toggle between the two batteries.
Is the alternator output @13.8v - 14.5v with the engine running?

[rossdg]

The alternator failed last year - new one fitted. LB is fitted and charged via a voltage sensing relay (smartcom). I recently discovered that the JVC audio system was drianing the LB (it is now wired so that it is only fed from the switched acc from the ignition. The interior and blinds are fed willinton style from the LB into the front of the fuse box. LB has also been replaced recently. The audio was constantly drawing 200mA through its permanent live (with face plate removed); currently (no pun intended) there is no measurable drain from either battery when the ignition is off. At idle the alternator is providing 14.4V, and drops to 12.8 when main beams, and aircon are running (though it does vary slightly - normal?).

The smartcom is working to spec - i.e. not switching over immediately after starting - though I have not measured the exact switch point.

[roofraisers]

Your Bongo might have one of them Japanese headlight dimmer systems fitted that dim the headlights when the engine is ticking over.Never seen one fitted but it has cropped up on the firum before.
http://www.igmaynard.co.uk/bongo/forum/ ... an#p438326

Nigel.

[rossdg]

Your Bongo might have one of them Japanese headlight dimmer systems fitted that dim the headlights when the engine is ticking over.Never seen one fitted but it has cropped up on the firum before.
http://www.igmaynard.co.uk/bongo/forum/ ... an#p438326

Nigel.

Yeah, thought of that, but no switch - and they only dim slightly. This issue has really only started to happen since last winter as far as I can remember.

[missfixit70]

I'm wondering if you disturbed/changed something when you movd the stereo wiring? Or did something in the wiring get hot & melt a bit causing a partial short somewhere? Can you disconnect the LB charging side & see if it still happens? Probably not it, but worth checking.

[rossdg]

I'm wondering if you disturbed/changed something when you movd the stereo wiring? Or did something in the wiring get hot & melt a bit causing a partial short somewhere? Can you disconnect the LB charging side & see if it still happens? Probably not it, but worth checking.

Should be simple enough - I have kept everything simple and accessable - but I'm wondering about that audio system; gonna start there and work backwards. I do have one of Haydns temp sensor fitted which also gives me SB/alternator voltage via the switched accesory feed as well.

Great response so far guys - but am I the only one experiencing the click when the foot is lifted?

[missfixit70]

Not heard of it before, that's why I was asking about alternator & batteries, wondered if it was the split charge relay kicking out as revs dropped? Not that that would explain the symptoms Worth checking all the earth connections etc, a friend was having sporadic alternator issues & it was down to the earth cable that looked ok on the outside but the cable had pretty much disintegrated inside, got a new one made up, problem sorted.

[rossdg]

Mm, after a little fiddling the mystery click seems to be related to whether the "Climate control" is on - in auto mode the "click" is present. However I can't confirm this 100% due to time constraints. Presumably if I have a dodgy earth lead then lack of current could cause aircon control to disable compressor? I'm assuming there is a relay controlling this?

[missfixit70]

Could be completely unrelated to revs, ac clicks in & out anyway depending on temp etc, but as it clicks in it will be putting more load on the battery/alternator. With the engine idling once it's warmed up, it should increase the engine revs via the 2nd vacuum solenoid on the drivers side of the engine (with a cold engine, the cold start solenoids should already be increasing revs, so it will probably drop a bit when ac kicks in until its warmed up to @55 degrees, if that makes sense).
Try it with the ac off.

[rossdg]

So after a trip to the Vendee covering 1800 KM I can confirm the click is actually 2 things:
1 - Aircon compressor (solonoid?)
2 - engine rev control (when cold)

Lights dim when aircon kicks in if revs drop (ie lifting foot from throttle): Voltage at tickover = 14.5v (even with lights on full beam), falls to 12.19v with aircon on.
Voltage at 1000rpm or more = 14.4v with everything on. So, is the new alternator not up to the job? Or as suggested earth dodgy (I have given it a non-destructive look over). Both SB and LB were holding charge at 12.8 volts after 250mile run down through France, and stayed that way all week. So voltage drop seems to be enough to dim lights (bulbs are Philips ultras +80%).

On another note head temp (rear mounted sensor) stayed between 75 to 85, rising to 91 when idling in a traffic queue (outside temp 26 deg C. Which I'm pretty pleased with following new rad and flush in february.

[David Edwards]

with mine it's my knees..