Question about Triumph Tr 7
Let us start with the draining battery first and with any luck we will hit on a solution with the the lights and wipers. With the battery still disconnected put a ammeter (just a cheap one will do) between the disconnected ground cable and the naked battery terminal and measure the residual current exiting the battery with everything 'off'. remove each fuse in turn, one at a time and record any drop in current before reinserting it. This will identify the circuit responsible for draining the battery. Classic examples are glove box lights staying on when the lid is closed because the contact switch mechanism has been bent out out shape; likewise trunk lights. Once you have identified the offending circuit leave the fuse out and find the relay on that circuit. On many cars individual relays have been combined into a multi-relay module. When you remove the cases for these modules the individual relay assemblies are still all there. A basic relay is usually a cube of about 25mm on a side with four pin connections. Two of the pins are for the low power signal or switch input circuit; turning your wiper switch on only uses a very few milli-amps and light weight wiring. The other two pins are for the heavy power circuit to operate the device requested by the switching circuit: the wiper motor circuit is a heavy power user and is supplied by heavier duty wires. For each relay, fed from circuit from which you have disconnected the fuse, check that the pins are clean and that the socket is also free of dirt, corrosion, water and any signs of obvious shorting. The relay casing will often have printed on the outside a schematic illustrating the pin designations and what they do. Applying 12 volts across the 'switch' pins will result in click as the 'power circuit' pins are connected. Check for continuity across the power circuit pins with the ammeter. If the relay seems faulty remove its cover (sometimes they have transparent covers) and look for obvious burns due to shorting. If everything OK check the wiring of the circuit from the relay to the component (tail lights, wiper motor etc). Disconnect each component in turn to determine device with power drain issues. The devices are usually grounded to the vehicle frame. THis process does not tell you directly what is wrong but gives you the correct approach of finding out. Experience shows that most failures of this type are due to shorting as a result of the effects of water, dirt, oil, and corrosion. Chafing of insulation is a close second.
Posted on Sep 27, 2010
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Posted on Jan 02, 2017
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