Right i know this may seem like im clasping at straws, but after having the car checked over by an auto- leccy today, he was baffled too,

alternators fine
as is everything else, supposably,


but just through chance, i hit the lock button on the window switch part of the drivers door somethnig i dont do much as its on auto lock, and like clock work , it flashes every time, asr/esp lights and loose connection, hmmm, i gave the inside of the car a good polish the weekend for mitcar, and thats when its started to be honest, so have i caused a short on the switch??,

that would also explain the power drainage of the battery with the central locking being active with the engine off, , i fitted a fully charged battery last night ( charged on charger) and by this morning it only had enough charge just to turn the engine over,

might be a red herring but might as well give it a try ,

so my next question is, how do I remove the switch cluster from the drivers door card? so i can at least check the connectors and test the switch


sorry for being a pain!,

I think you can just pull the switch out, it just levers out on mine... but thats my car lol worth a shot!!

haha , cheers! anyway but bingo! just found out for sure its a new alternator!, old one seems to be giving out spikes up the revs, checked it with meter and yes its giving out 14.1v but its randomly jumping up and down, and a slight smell of electrical burning under the bonnet,


so fingers crossed!, will be a new car by the time ive finished replacing things!

cliche as it sounds, i was thinking about this today on the way home from work and shopping and i was going to suggest monitoring the alternator output to look for drops, rather than spikes. you got there first!

Steely said:

haha , cheers! anyway but bingo! just found out for sure its a new alternator!, old one seems to be giving out spikes up the revs, checked it with meter and yes its giving out 14.1v but its randomly jumping up and down, and a slight smell of electrical burning under the bonnet,

Click to expand...

Ben, I wouldn't be too quick to jump to conclusions on this as an earthing issue is still a possibility (most common problem on the Stilo by all accounts)

This is the thread which drove Decks and I nuts trying to make sense of although there was a very good outcome in the end.

Give this a read and concentrate on the earthing tests

cheers argo, ive had a good look but every earth is tip top, resistance checks dont go beyond 0.02, which is good, even tried doubling up just to make sure and it still does it,



how good is this! friday night trying to sort the car

right been doing some more testing,

bit of advice on these results if possible!

car idle no lights on, battery running ..................14.0 volt

car idle With lights on (+ full beam) ....................13.7 volt

Car idle with as many ancillaries as possible on...... 13.33volt


It seems the fault comes up when a sudden loss of voltage occurs, ie when I lock the doors, it will for a second drop from 14.0v to 13.2v then back to 14.0v, beep beep beep loose connection!!!!!

should the rectifier keep the voltage level tighter than that?? I gave the alternator a liberal spray of wd40, and suprisingly the battery didnt go flat last night??

Those readings look very good and the only thing that is wrong is why the voltage drops when the fault occurs.

You say you've checked all the earths. It's actually more accurate to measure voltage drop across the earth leads and this should not be more than 0.2 volts (and most importantly not change when the fault occurs).

Don't forget to measure chassis earth to engine block too as this was very suspect in that thread you've just read.

If all the earthing results are good then there is only one posible conclusion. Something on the car is taking a heavy current drain for a very short period. Find what's taking this extra current and you've found your problem. In reality it's most likely something shorting but resistance within other parts of the circuit means you only see a drop of 0.8V at the battery. Remember, everything electrical on the cars only drops it by 0.67 so the load must be huge to drop by 0.8 volts

Keep checking stuff with your voltmeter and look for big swings (when fault occurs) and this should lead you closer to the fault. Remember too, something MUST be getting hot when the fault occurs.

Ben, strictly speaking (if earths are all good) then the alternator could be suspect too as you suggested yourself.

An easy way to prove this is to measure the voltage drop across one of the main earths.

When the fault occurs:

• If voltage rises then you have a short (as per last post)
• If voltage drops then it's the alternator.

once again cheers for the info argo, its been really bugging me up to now!, so ive done 3 vids to show you whats happened today,

first thing i did this morning was get some proper contact cleaner and clean everything going, d4, the lot, job done, had all the earth cables off, wire brushed the contacts, cleaned the areas they fix, and with a little bit of copperslip reconnected them,

ive got a new alternator but havent fitted it, as im still not happy, even though its showing more that way now,

this is the first vid, after a 20 min drive, it was all quiet at first, no lights nothing, but about 10 mins in all hell broke loose, fecking chrimbo tree for a dashboard losing milage display, temp , hunting at idle and a voltage fluctuation,

make your own decision on this one! you can see a voltage drop in relation to the hunting, and the dash, oh well only a few months off christmas!,



lights on
engine running on idle just after 20 min run



voltage check at idle , hunting in relation to voltage drops (LIGHTS ON)





engine off just after 20 min run, and voltage readout

voltage check this morning 12.3v

wow, somethings fried somewhere.

stick that alternator on and see how it goes.

I had electrical problems in a seat ibiza and it was a failing alternator

Anyone got any advice?? Dont want to fit the alternator if its not that, 120 quid for a recon one, so once fitted no comeback,

apart from that im stumped

Big Black Stilo said:

apart from that im stumped

Click to expand...

in the same boat mate!

Looks a circus

Too much going on. What I would do is eliminate the alternator from the equation by simply slackening off the alternator drive belt just enough so it's not pulling the alternator around or, just remove the belt (Don't do it the other way though and run the alternator without being electrically connected). Just run the engine in your driveway as it won't last forever just running on the battery

I forget what engine you have and the drive belts vary a lot so obviously if you have an aux belt driving other stuff like water pump then don't test engine run for too long. If you have just a drive belt just going from crank pulley to alternator then there's no worries



Your battery voltage looks good and it's holding charge fine.

Your engine tickover is oscillating in tune with the voltage and can't tell whether there's an electrical load making the engine rpm drop or whether the alternator is partially dropping out. It certainly looks like alternator voltage regulator problem or an internal diode causing problems.

I'd try it without the alternator running and see what happens to tickover and warning lights. You'll get a few of course but hopefully not the xmas tree every few secs

right ive gone for it!, good learning curve anyway!,

had to kill the precat labda to get it out couldnt get to the bolt at the back of the alternator with the big manifold shroud in the way, , tried with a lambda socket but just skipped, loads of wd soaked in and so on but woulndt budge, so hacked it off, and got a great big torque wrench on it! sorted!


until i saw the price of them , whers the best place to get one at a reasonable price?? ive seen these universal fit ones but im not happy about using one really,

Universal sensor around £40 (have to do your own connections)
Shop4 parts around £60

your voltage tests with engine running suggest alternator is fine. this is further backed up by the fact that a fully charged battery lost charge overnight, an alternator fault cant do that, there must be a drain (although a faulty battery could also explain it).

a drain is often a sign of a short due to a fault in a circuit's wiring or one of its components. that short can cause all sorts of electrical faults depending on where it is, including the problems you are experiencing.

the first thing you should do is measure the drain. use a multimeter set to measure current (amps). disconnect the battery negative terminal and then connect the meter between the earth lead and negative terminal. the amp reading tells you the drain on the battery. report your result in this test so we can determine if a drain is occuring.

next you need to identify the circuit that the drain is occuring in. to do that leave the meter reading the amps and then remove one fuse at a time from your fusebox. the fuse that makes most of the drain reading drop off is the fuse for the curcuit causing the drain. remember that anything electrical that you have installed such as an amp needs to be tested seperately because it will not have a fuse in your fuse box.

once you know which circuit is causing the drain you can do test on that circuit to see if there is a wiring fault or component fault, obviously i cant give more detail on how to do that until i know which circuit is causing the drain.

Ooo no Jug. I know it's a guessing game with intermittent faults but that's some wrong statements there and we don't want to confuse Steely

a fully charged battery lost charge overnight, an alternator fault cant do that,
Yes it can and often does, it's one of the most common alternator faults there is. Think about it. the alternator is directly connected to the battery positive and it's casing is connected directly to earth and the only things stopping current flow are its internal diodes- the most common breakdown of an alternator

your voltage tests with engine running suggest alternator is fine.
No. The movie voltage tests suggest the alternator isn't fine at all. It hardly ever gets above 14v, struggles to maintain even 13.7v with just lights on and often dips below 13v so it's only the battery holding up the circuit. That's not a fine charging circuit at all.

The output should be much higher than that and rock steady
Here's a Stilo under various loads so you can see what you're aiming for


Stilo just started with no extra loads


Stilo just started with headlights on too (that's 14.28v)


Stilo 5 mins after cold start with headlights, hrs and heater fan on

The voltage should be real steady and holding throughout all these tests

Steely's voltage shows weak output and struggling to maintain voltage

Quite so Decks

....although it has to be said Steely didn't say where his voltmeter was connected.

Most importantly, we're trying to track down an intermittent fault so static tests are pretty pointless anyway.

What Ben should be looking for is the biggest percentage CHANGE in voltage or current when the fault takes place. It's quite tricky measuring voltage as obviously car wiring tends to be well isolated and protected. One very useful device for measuring current (AMPS) is a field effect meter which simply clamps around the wiring which means you don't need to damage the isolation.

They're a bit pricey but a good car auto electrician should have one (perhaps Ben could borrow one :chin

As it stands, I'd agree it's best to get the alternator out of the equation (not familiar with the 1.6 so not sure what happens if you loosen the belt) but with a really good meter you should be able to prove the case (post #48) without removing anything.