RE: [doc] Gauges and electrical gremlins

["Chris Parnham" <chrisparnham1@xxxx>]

Sounds like a bad earth to me.
Chris Parnham

-----Original Message-----
From: jchapelhow [mailto:chapelhow@xxxx]
Sent: 20 July 2003 16:35
To: doc-uk@xxxxxxxxxxxxxxx
Subject: [doc] Gauges and electrical gremlins

All

In order to continue the diagnosis of my overheating problems I have
invested in a non-contact digital thermometer. Point the laser beam
at an object and, hey presto it tell me how hot it is. No more
guessing or burnt fingers!

It would seem that my immediate, genuine overheating problems have
been corrected by the new silencer/cat-bypass. After a 25miles run,
both pipes to and from the thermostat recorded ~65degree-C. Even
allowing for a 15-degree-C difference across the metal of the pipe
the cooling system is doing the business. The cooling fans therefore
do not need to come on at all, which Martin and others advised was
the best indicator of excess heat being generated.

The problems now seem to be electrical with all of the gauges doing
some very strange things.
· During the trip, the temperature gauge in the car varied
wildly, settling at around the 10'oclock position. When the ignition
switch is turned off the gauge initially settles to zero. Then it can
be watched to climb to point straight up, ie beyond the normal top
scale. Indeed on several occasions the needle settled pointing to the
letter P, of `temp'. The gauge rises very quickly if the lights are
switched on, faster as each greater level of illumination is used.
The temp gauge also moves when the interior cooling fans are turned
on/off.
· The voltmeter now rarely indicates above the 8v mark.
Occasionally is will read 10v if the car is revved at idle. Attaching
a voltmeter across the battery shows it to be OK, and starting is
fine. New 130amp alternator is standing by but the car has a Motorola
that appears to work correctly.
· The oil pressure gauge, for which a new sender has been
fitted, does not read beyond the second line. The pressure has been
checked by external equipment and is OK. The gauge moves about
through an angle of 30degrees and back when the door sensors are
open/closed.
· Petrol gauge reads low. The car has a full tank of fuel, but
points to <quarter full.
· The direction indicators are not behaving either at idle at
junctions the indicators do not start working, if the throttle is
blipped they start, but I am not confident that they are working as
quickly as the should. Hand signals through the minimal window are
not a good option!

I am guessing that there is either a bad ground or a short somewhere.
All of the relays/fuses have been upgraded. The new lock zilla and
fan fail 2x2 work normally. I had planned to change/clean the relay
for the direction indicators but the manual shows this (and the
windscreen control module, logic/buzzer box) next to the left hand
bulkhead. No such device is immediately visible. (Still trying to
trace the buzzer noise)

I have briefly connected a jump cable between the -ve battery post
and the engine ground point which made no difference.

What are the next steps to diagnose where the problem lies? The car
itself drives very well, and the engine now revs smoothly. I am
concerned though that I am being denied meaningful warnings of actual
problems, and I am now spending too much time staring at the
direction indictor bulb to see if my signals are being shown to other
road users.




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