Electrical Gremlins, a shock to the system

["jchapelhow" <chapelhow@xxxx>]

All.

Long update after speaking to various members of the team at Gaydon.

'Boeing' made it home OK, unfortunately as before I could only choose 
1 electrical system at a time, lights/fans/windscreen wipers all had 
to be truned off for the indicators to work. Any electrical gizmo 
controlled form the front of the car (headlights/hazard lights/stalk 
functions/haeater etc fuction caused the temp gauge to fly up, the 
oil pressure gauge to drop to zero and the battery and fuel gauge to 
oscillate wildly. The electric windows behave fine. I now own a non-
contact thermometer so that I can check that the temperature of the 
engine is NOT that hot, but it is alarming to see the gauges.

I have now replaced my battery with a 100amp-hour 600CCA maintainance 
free from Partco ~£52. My car did not come with the original side 
attachments, it came with a modern square top job. Apparently Dave 
Howarth can still get the original style for those of you who have 
the connectors...

I have instead bought a 'standard' post type and have visited Maplin 
electronics to get solid brass (gold plated) convertors so that I now 
definately have good contact with my cut-off switch connectors, plus 
it looks cool. (£2.99 each post).

I purchased replacements for the main/accessory relays. Hella 70amp @ 
12v/80oC £18.45 each from Andrew Page Ltd (4RA003437047).

Then I set to work with my new Automotive Electronic tester (current, 
voltage, resistance, rpm ,dwell etc £19.99 from Maplin).

Here I found that the metal panel around the lock modules was at 12V, 
er that's not right then? Several cups of coffee later I traced the 
fault to the thermal trip circuit breakers which I replaced (wiring 
very untidy at the moment). The central locking is now working again 
fully, obviously the lockzilla was compensating for a more severe 
problem than I had realised!

All that done, I then retested voltage at the battery=alternator, 
voltage increases as per the manual when engine is running. With the 
above updates I could then run two things simultaneously, aha 
progress! 

The only minor quirk was that now my buzzer didn't sound for the door 
open and the seatbelt warning light had stopped. Much of the wiring 
loom on my car seems to have been amended, the buzzer box was not 
where it appears on the diagram. After some searching I found it 
BALANCED on the top of the heating duct next to the steering wheel. I 
was trying to jiggle wires to see if I could get it working when it 
fell from there, causing a shower of blue sparks as it hit against 
various metal components. Considering I was wedged upside down below 
it reaching for the wires this came as a bit of a surprise...

I disconnected all of the wiring connectors and untangled the wires 
which seem to have been trimmed. This resulted in much swearing and 
the door sensor being damaged. The black metal piece which holds the 
buzzer/logic box/indicator relay is now dangling next to the clutch 
pedal, does anyone have a picture of where this should go? The are no 
holes cut into it and no obvious mount points on the bulkhead. 

Too dark now to continue tonight....


John Chapelhow
DOC 19 : 'Boeing' 0737