Post Number: 34
|Posted on Friday, 27 April, 2018 - 07:18 pm: |
What is one of the worst things that continually plague us, as owners of classic Rolls-Royce and Bentley cars and perhaps we donít know it?
It must surely be the inability of previous owners to modify the wiring diagrams for our vehicles as changes are made.
I have a few examples from my own experience with my 1938 Wraith WXA68, 1951 Bentley Mk VI Special B25KL and 1978 Corniche DRH32489 as outlined below.
At some stage in the past, the wiring was modified after changes to the air conditioning system. Amongst other things, a switch was placed in the handbrake area, which apparently allowed the aircon unit to be bypassed. This seems to have been required since the fuse kept blowing after the new compressor, with higher current demand, was installed.
The oil level switch function was modified so that, when pressed, the fan selector switch could be turned to allow the fan to be run at maximum!! Other modifications including elimination of the rear fog lights have been made.
Bentley Mk VI Special B25KL
This vehicle has, in the past couple of years, undergone numerous modifications, including a major revamp and a complete rewiring. The auto electrician who did the rewiring work included changes to the wiring without reference to me, for example changing the function of the main switching facility and incorporating an oil pressure switch to prevent the petrol pumps running before the oil pressure becomes positive.
The Wraith was modified over the years, starting from a complete restoration in 1984. Things which were changed over the years include the elimination of the side turn indicators and replacement by modern turn indicators, installing a pilot indicator for the turn indicators, introduction of a remote isolation solenoid for the battery, addition of an overdrive unit, and installation of a modern Bluetooth operated sound system etc.
In none of these vehicles was the wiring diagram updated at any stage, and now I find myself often struggling to deal with some electrical problems due to a lack of information.
This was brought to a head when a few days ago on the way back from the RROCA National Rally at Clare, SA where I was returning home to the Gold Coast in my Wraith. I had problems with the overdrive control, and eventually I overcame them, but I blew a fuse while testing circuits. Unfortunately, no one knew where the fuse for the overdrive was located, and I drove the last 1500 km without the benefit of the overdrive to get home.
A couple of days ago I found, after painfully following the lead from the dash mounted overdrive switch, the power source and the blown fuse. This was tedious, since I had to remove all the cable ties as I separated the one particular wire from all the other almost identical cables winding their way through the nooks and crannies of the bodywork and the chassis.
I have now drawn the electrical circuit for the overdrive system and will modify my copy of the wiring diagram to incorporate the modifications associated with the overdrive unit. More work needs to be done to fully update the wiring diagram for other changes, but it highlights that we should all keep tabs on our electrical modifications to our vehicles and properly document all changes.
We owe it to our subsequent custodians of our vehicles to ensure our wiring diagrams are current, with explanations where fuses, switches and other pieces of new or modified equipment are located and their place in the overall wiring of the car.