306 meridian fluctuating voltage

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Wed 14 Jan 2004 11:38
306 meridian fluctuating voltage - MattK
Hi

First post on here. Wife has a 97 306 meridian which has developed a strange voltage problem. Essentially the interior instruments brighten with increasing RPM and vice versa. Temp gauge has also become voltage dependant, with increasing loads, (lights,heaterblower) causing it to rise. I assumed this was the alternator voltage reg but a test at the battery sees 14.5v stable with the engine running. Switching on absolutely everything shows no fluctuation in voltage with it dropping a tad to around 14.3V. Therefore what I want to know is, is there another voltage regulator withing the car? Or am I missing something.

Matt
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Wed 14 Jan 2004 12:18
306 meridian fluctuating voltage - solara
I believe there is a dashboard voltage regulator. I am sure someone will soon pass by and let us know where it is on the 306. My guess is it is attached to the dash display.
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Wed 14 Jan 2004 14:55
306 meridian fluctuating voltage - Peter D
Yes there is a regulated feed for the gauges but I do not believe it supplies the dash illumination bulbs as they only come with side lights. I would suggest you have an earthing problem and that is why the lights get brighter with the increased load. Are you sure it is effecting the gauges. I'll pull a manual for it later today and come back to you
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Wed 14 Jan 2004 17:42
306 meridian fluctuating voltage - Peter D
The illumination lights in the Instrument panel are not regulated as I thought, nor, it appears are the gauges so a possibility is that you have two earth straps, one from the Negative directly to the transmission housing/engine block and a second from the neg to the body work. If this boby work earth strap is at all corroded and few milli ohms of resistance is in that link then the increasing the load, i.e. fans, lights etc etc with cause current to be drawn from the alternator through the earth strap thus effectively causing the body zero volts to move further away, in terms on volts, from the positive terminal. You are probably seeing the effect of less than a 1 volt increase but you must find the fault as if the resistance goes any higher all sorts of things will stop working including your ECU. Connect a meter directly onto the lead negative terminal and the body work then get someone to turn on the loads, you should measure hardly anything. Regards Peter
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Wed 14 Jan 2004 17:46
306 meridian fluctuating voltage - MattK
Thanks Peter
I'll check it out later and post a result should I find one.
Matt
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Wed 14 Jan 2004 18:34
306 meridian fluctuating voltage - Peter D
If that is not you prob then measure the voltage on the Instrument panel fuse to see if it is the same as the battery voltage, It may be you have a low voltage in this fault mode and the brightening is only when the voltage comes up to its proper voltage Cheers.
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