QuestionHello,
I have a 1979 MGB. The temperature gauge quit working a while back. I bought another and installed it and it still is not working. I bought a temperature sending unit and installed it and it is still not working. A few evenings ago as I was driving home the headlights started blinking off and on. My first question is what else can I try to make the temperature gauge work? Secondly, could the headlight problem be linked to the temperature gauge problem? Thank-you for any help.
Kathleen
AnswerHi Kathleen
You have two separate problems here. Let's look at the gauge first.
Get a helper to turn the ignition on. No need to start the engine. Unplug the green wire with a blue trace from the temperature sender and touch the wire to earth (e.g. the metal base of the sender). Ask the helper to tell you if the needle on the temperature gauge moved while you held it there. Do not leave the wire connected for more than a few seconds. If the needle moves, the wiring and the power supply are ok and you have another faulty sender.
If it doesn't move, then the fault lies with the wiring to the gauge. The gauge itself is very reliable and seldom causes any trouble. The power supply to the gauge is shared with the fuel gauge, so you could bypass the wire from the fuel gauge (light green with a dark green stripe). If that is OK, then the green wire with the blue stripe has a break in it somewhere.
The lighting problem sounds more serious. You don't want to drive home without any headlights. It will probably be the switch. These do give trouble. Replacement is easy, but remember that the brown wire is permanently live, so disconnect the battery before you remove the old switch.
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There could be a problem with the earthing of the headlamps. If you lift the bonnet (hood) and look behind the radiator grille, you will see some wires and some bullet connectors (both sides). These connectors get a lot of muck on them in wet weather, and they do corrode. There are a bunch of wires coming through a grommet at the side - trace them from behind each headlamp. Remove the radiator grille (just held in with a few Philips screws). Find the BLACK wires, and trace them to the push-in connectors. Pull each black wire from the connector, clean it, and put it back in again. You may need a slip-joint wrench to press them back in. If the metal clip inside rubber connector is badly corroded, replace the connector. They cost pennies.
Let me know how you get on
Merry Xmas
Barrie Jones
