Vauxhall Corsa C (2000 - 2006) - 03 1.0 electrics and speedo problem

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Thu 12 Feb 2009 20:11
03 1.0 electrics and speedo problem - scarface37
Hi

I am having a nightmare with a 52reg(03) Corsa 1.0

During the winter of 2007, the speedo started to fluctuate up and down very badly. We got this checked by a local auto electrician (Spending £100) and he said he thought the speedo itself was defective and quoted £500 to get it sorted.

However, we subsequently checked the battery which was in a poor state and replaced it. The car then did 6000 miles through all weathers without any trouble.

Then in November 2008 it started again. So we checked the battery. Again it was looking a bit sick for some reason so we replaced it. The car then did 600 miles before the fault returned once more.

So I fitted a Vauxhall battery, thinking that the cheaper type of battery wasn't as good, but this made no difference.

Then we started to look at the voltage regulator (Which is part of the alternator?). We had the voltage output tested. When you first start the car, output was fine, but upon switching on any consumers such as lights, heated rear window etc, it went into total discharge, which we thought would logically mean a bad alternator.

So we replaced the alternator.

The car then ran for 180 miles through all weathers, freezing cold temperatures etc.

Then the fault returned AGAIN!!!!!

Checked the battery and it is showing approx 40% charge and 30% health.

Why? Why isn't the new alternator charging the battery????

The fault with the speedo always occurs when the battery is showing this kind of read-out.

This fault is driving me mad as its the wifes car and she is giving me grief.

Anyone who knows anything about the electrics on this car please help as I am seriously thinking of selling the flaming thing.

Is there a voltage regulator elsewhere on these cars that could explain why a new alternator is discharging a new battery???????? I have asked the local Vaux dealer and ascertained that there is no regulator at the back of the instruments as found on earlier models.

Note I have checked the speedo block connector and that is fine.

The fault is worse the colder the weather for some reason. I'm convinced that the problem lies with the electrics somewhere. Anyone know the location of the earth points?

I the last few days I noticed the the engine idle also suffers a slight fluctation in tandem with the speedo (Which is weird yeah???). Could this be an ECU issue????

The car can also sit stationary with the speedo reading 50mph! And its clocking miles at the same time!! Anyone got any matches????

Edited by Webmaster on 12/02/2009 at 20:43

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Thu 12 Feb 2009 22:18
03 1.0 electrics and speedo problem - elekie&a/c doctor
I would suggest get an auto-elect tech to check the voltage drops on both the power and earth wires to and from the alternator/battery and chassis earth points.Any problems here can cause a malfunction of the electronics to engine Ecu and dash.hth
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Fri 13 Feb 2009 11:25
03 1.0 electrics and speedo problem - scarface37
Thanks for taking the time to reply

An auto electrician checked these areas 12 months ago for £90 but couldn't find the reason. He was all for replacing the instrument cluster.

I've been on other forums and the opinion is it could be a voltage stabiliser problem causing the speedo fluctuation. I have seen this fault where the speedo responds almost as a "Rev counter" when you blip the throttle.

The thinking is that the voltage feed to the instuments is not being stabilised as it should be.

I am now trying to establish whether a Corsa C has an internal voltage stabiliser within the instrument cluster (On previous models it was fitted externally).

If I can conclusively establish this I will most likely fit new instruments.

Thanks once again
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Fri 13 Feb 2009 11:33
03 1.0 electrics and speedo problem - Peter D
You have made no mention of the speed sensor in the gear box or provided any voltages. I suspect there is a stabiliser in the instrument pod but it will also feed the temp and fuel gauge and you make no mention of them mis-behaving. Regards Peter
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Fri 13 Feb 2009 12:36
03 1.0 electrics and speedo problem - Dynamic Dave
You have made no mention of the speed sensor in the gear box ....


The speed sensor on Vauxhalls is usually in one of the hubs.
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Fri 13 Feb 2009 16:28
03 1.0 electrics and speedo problem - scarface37
Hi

Yeah one of the first things we checked was the speed sensor on the hub. Nothing wrong there though!

As far as the instruments go, its mainly the speedo that shows issue, though I have seen the rev counter misbehave in the past. The temp and fuel guages have never had any issue.

This would therefore rule out a voltage stabiliser issue?

I spoke to someone today who suggested it could be a dry joint in the instruments??? Any opinions on this possibility.

Before I had the alternator swapped we checked the amperages and it was putting 7 amps into the system. We also checked the voltages (No figures at the moment), but the car was ok on start up, but once any consumers were switched on the readings went into total discharge. When the wife's driving the car, she finds that if she switches everything off the speedo will just waver around the approximate speed.

Thanks for replying
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Fri 13 Feb 2009 17:52
03 1.0 electrics and speedo problem - Peter D
Thanks Dave.

OP how was the sensor tested did they check the ouput waveform from the Hub speed sensor. Regards Peter
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Fri 13 Feb 2009 18:27
03 1.0 electrics and speedo problem - SpamCan61 {P}
Personally I think you need to sort out the battery discharge problem starting at the alternator and working through the circuits - I suspect (just gut feel, no evidence) that the speedo fluctuation etc. is being caused by the drop in battery voltage.

Have you monitored the battery voltage, and maybe the accessory voltage - at the cigar lighter point for example - when this weird stuff is going on?

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Fri 13 Feb 2009 21:55
03 1.0 electrics and speedo problem - SpamCan61 {P}
Thinking a bit more,what are the voltages at the battery? You should get 12.6V with the ignition off, around 14V with fast idle but no load,dropping to about 13.5V with headlights etc. on. Hopefully someone can correct my figures if they're a bit out.

The fact that it gets worse the colder it gets points the finger more at the battery than the alternator I reckon, but some voltage measurements would be good.
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Wed 11 Jun 2014 23:40
03 1.0 electrics and speedo problem - focussed
I would suggest get an auto-elect tech to check the voltage drops on both the power and earth wires to and from the alternator/battery and chassis earth points.Any problems here can cause a malfunction of the electronics to engine Ecu and dash.hth

On the right track there I think-I had the exact same problem with an E34 BMW 520 for months-traced to a loose earth bolt where the battery negative lead is connected to the body underneath the front of the rear seat.

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Tue 10 Jun 2014 20:43
03 1.0 electrics and speedo problem - Andycarpets

Hi there, I have the very same problems in my 04 1.7dti combo van.

Driving me crazy. nobody seems to know why its doing this. If anyone else has had this problem please help.

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