At 09:57 AM 8/1/00 -0400, Stephane St-Amant wrote:
>
>Sunday, I decided to tackle the electrical system. More precisely, the
>lights all around the car.
>- Headlight? Check
>- High Beams? Check
>- Rear Parking Lights? Check
>- Blinkers? Nope, Flasher unit need to be replaced
>- Backup lights? Nope, both bulbs are blown, will replace
>
>Now, here's where I'm stumped (I check the archives but coudn't find
>anything similar)
>- Brake Light? Nope
>- Check the light bulds - Look OK
>- Clean the connections
>- Test - Works... Try again, don't work...Hummm
>- Get my trusty voltmeter (about 20 years old - never failed me.
>- Check the current at the socket - Pedal released: 0 volt, Pedal Pressed:
>12 volt - Good
>- Put the light back in and test: Not working
>- Check for continuity in the bulb (with the voltmeter/tester): OK Double
>Hummmmm......
Steph,
I'll be you have 1 of 2 problems:
1. Most likely a bad ground connection at the light. If the ground has
a high resistance, then it can carry enough current to light the bulb,
but the hot side of the circuit will show 12V.
2. The hot wire has a very dirty connection someplace, or many of the
strands in the wire are broken. Again, this will cause a high resistance
(to current flow - not noticable with an ohm meter) and not let
enough current through to light the light.
To try and figure out which wire has the problem:
1. Disconnect the neg. side of the battery. ALWAYS do this before you start
playing with any of the wiring. It's too easy to let a hot lead touch
something that is ground and start blowing fuses, or burning up wiring
harnesses.
2. Remove the hot wire from the back of the light socket.
3. Take a spare piece of wire - anything 18guage or larger will work,
(I keep lots of alligator clip leads around for this.) and connect
it to a good ground. You may even want to use a very long piece of
wire and connect to the Neg. side of the battery.
4. With the hot wire under control - not touching anyting - connect the
neg. lead back to the battery.
5. Hold the end of the "ground" wire to the metal case of the light bulb
and touch the hot lead to each of the tits on the bottom of the bulb.
If the light goes on, you have a bad ground. If not, you have a bad
hot wire.
6. If the hot wire is bad, trace it back towards the dash. At each connector
disconnect the wire, and try finding the hot lead on the dash side.
Try step 5 again. When you finally get the bulb to light, you've found
the bad connector.
As Douglas Braun Papakonstantinou points out:
"Those little 4-way bullet connector blocks often fail. The
metal contacts inside them start cracking and falling apart.
Order about ten of them (they are cheap), and check and possibly
replace every one you can reach. There are at least three of them
in the trunk, and three more for the headlights and front parking
lights in the very front of the bonnet."
If the don't break, they are very susceptiable to corroding. To fix this
get some phosphoric (sp) acid (also know as metal prep or OSPHO). Put a
little in a small plastic container. Dip the bullet ends in the acid to
clean the oxidation off. Then wipe dry with a paper towl. For the
cylindrical connectors you can drop them in the acid, or use a cotton
swap, dipped in the acid, and push the swap through the connector. This
will clean the inside.
Before you push the bullets back into the connector, put a dab of dielectric
past on the bullet. This will keep the connectors from corroding in the
future.
Hope this helps.
John
John T. Blair WA4OHZ email: jblair@exis.net
Va. Beach, Va Phone: (757) 495-8229
48 TR1800 48 #4 Midget 65 Morgan 4/4 Series V
75 Bricklin SV1 77 Spitfire 71 Saab Sonett III
Morgan: www.team.net/www/morgan
Bricklin: www.bricklin.org
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