In a message dated 97-04-19 16:00:46 EDT, WDKLINE@aol.com writes:
> The temp and fuel gauges on my TR4 both quit working. Checking the
schematic
> in Bentleys shows that they both get power from the voltage stabilizer.
> According to the book, the voltage stabilizer puts out a constant 10
volts
> and the gauges are bi-metal devices - the senders flow current according
to
> either coolant temp or the float position in the tank. I ordered a new
> voltage stabilizer since its a sealed unit and the trouble shooting method
> is
> "compare to a known unit". I bench checked the new unit and found it only
> puts out 4.8 volts. With the new unit installed, the gas gauge maxes out
at
> half full. This makes sense it the gauge is looking for 10 volts. Not
> being
> fond of the random replacement of parts on a repetitive basis.....
>
> Anybody have any experience with this problem? Could be as simple as VB
> sending a bad/wrong part but you can't talk to anyone who knows anything
at
> VB. I'm begining to believe Lucas truly is the Prince of Darkness.
>
> Thanks,
>
> Bill
> 62 TR4
Bill, sounds as if you have identified the problem. When you bench tested it
what was the voltage whch you applied to the "B" terminal on the stabilizer?
If it was a solid 12v then it appears that the stabilizer is no good. [BUT
in Ken Ball's Autobook for the TR4, he says that it takes two minutes for the
stabilizer to read 10V. He is testing it in the car using a Smiths
Automotive Instrument Tester connected to the stabilizer ( "I" terminal) and
to ground. The time could be for the tester itself to read properly but he
doesn't explain if that is so. Conjecture on my part says to try 12v on the
"B" terminal for two minutes and see if the voltage comes up to 10v on the
output. If not I would say you have a wrong or bad stabilizer.
If the stabilizer is OK then the only other thing I can see from the
schematic in Haynes (don't have my Bentley's handy) would be low input
voltage to the stabilizer. Did you check the voltage at the input (the green
wire connected to the "B" terminal on the stabilizer). It comes through the
ignition switch from A1 on the control box. The output at A1on the control
box should be 12v with the engine off but ignition on and 12-13volts with the
engine running at 1000rpm (ignition warning light off). The next place to
check would be at the ignition switch and then finally at the input to the
stabilizer.
Hope this helps.
Art Kelly '64TR4 CT33118L
VTR TR4 vehicle consultant
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