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Re: Electrical Problems

To: rhansen@att.com, triumphs@autox.team.net
Subject: Re: Electrical Problems
From: DANMAS@aol.com
Date: Tue, 13 Apr 1999 21:03:28 EDT
In a message dated 4/13/99 8:52:27 AM Eastern Daylight Time, rhansen@att.com 
writes:

>  I discovered a problem
>  with my lights. Here are the lights that DO NOT WORK:
>  Instrument lights
>  All 4 side lights
>  Back-up lights
>  Rear lights (stop lights work)

<snip>

>  But, I thought that there might be two things out there in TR Land: an 
exact
>  idea of which fuse controls which lamp and also some ideas as to how to 
best
>  troubleshoot this problem. After all, April 23rd is fast approaching and I
>  still have some other things to chase down before I go before the ever
>  powerful Gods of the DMV.

Red,

The instrument lights, the 4 side lights, and the rear lights are all fed 
from the same fuse - the one with a Red/Green wire on one side and two or 
more Red wires on the other. This fuse is powered from the headlight switch 
via the Red/Green wire, and all the devices fed from it are fed by the Red 
wires. Your license plate lamps and the front marker lamps are also fed from 
this fuse. If any of these lights are working, then your problem is not in 
the fuse. Somewhere, probably under the dash, one of the Red wires has come 
loose.  Of course, it's entirely possible that you have more than one problem 
with the wiring. Check all of the Red wires and their connectors.

If neither your license plate lamps nor your front marker lamps are working, 
but the headlights are, then check your headlight switch to see if you have 
power on the Red/Green wire on the switch with the headlight switch on. If 
not, you have a bad switch. If you do, then there is a break in the Red/Green 
wire between the switch and the fuse.

Once you have found the problem, it's still quite likely that the instrument 
lights will still not work, because of the dimmer in the circuit - this is 
notorious for failure. I would recommend connecting the Red wire and the 
Red/White wire on the dimmer together and just eliminate the dimmer 
altogether.

The back-up lights are fed from the fuse with the White wires on one side and 
Green wires on the other. This fuse also feeds the WW wipers, heater fan, 
turn signals, gauges, and the brake lights. Since most of these items are 
working, the problem is not in the fuse. One of the Green wires from this 
fuse runs to the switch on your transmission, which is closed when in 
reverse. From the other side of the switch there is a Green/Brown wire which 
goes to the lamps. Check to see if these wires are correctly in place. If so, 
look for power on the Green wire  (with the key on), and then with the 
transmission in reverse, check that you have power on the Green/Brown wire at 
the switch. Note: you may have two other switches on the transmission as well 
- one for the neutral safety switch and one for an OD circuit -- make sure 
you are looking at the right one.

If you don't have power on the green wire, there is a break in that circuit 
which needs to be found and fixed. If you have power on the Green wire, but 
not on the Green/Brown, either the switch is bad or misadjusted. If you have 
power on the Green/Brown wire, then there is a break somewhere in the that 
wire on its way to the lamps.

I think that just about covers everything, and I don't believe I have any 
errors in it. If I can be of more help, let me know.

Dan Masters,
Alcoa, TN

'71 TR6---------3000mile/year driver, fully restored
'71 TR6---------undergoing full restoration and Ford 5.0 V8 insertion - see:
                    http://members.aol.com/danmas/
'74 MGBGT---3000mile/year driver, original condition - slated for a V8 soon
'68 MGBGT---organ donor for the '74

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