Noah :
Well, for starters, you could include what car and commission number you
have in your posts. It does make a difference sometimes, for instance
if you have an early "curved glass" TR4, then the fuel/temp gauge
problem has to be a bad ground to the gauges. If it's a later "flat
glass" TR4, then the problem is likely a bad ground to the voltage
stabilizer (and the gauges don't have to be grounded at all).
Note that the fuse ratings are given in the "British system", which is
somewhat higher than the "American system". Both TR4 fuses are 35 amps
"British", which according to Buss, makes an AGC 25 a suitable
replacement.
The lampholders for the turn indicator and ignition lamps on TR2-4A are
pretty bad IMO, my guess is that after your fiddling, the bulb is not
making contact in the holder (or the bulb died). However, there is a
separate ground wire required for the turn indicator lamp, so that could
also be a problem.
The ignition lamp/ammeter problem is likely to be something else, and is
probably more serious, since it's likely the battery is discharging.
First, if you don't already have one, get a multimeter, preferably a
digital one. (Some people prefer analog, and they are better in some
specific cases, but digitals are far more rugged.) Harbor Freight
frequently has one on sale for under $10 that will do for basic
troubleshooting. In fact, I'd suggest getting a cheap one to keep in
the boot, even if you have a better one to keep in the shop/garage.
Also get a package of "clip leads" (jumpers with alligator clips on each
end) from Radio Shack; keep a few of those in the boot.
Some basic charging system tests (note that if your car is positive
ground, all the voltages are negative) :
Engine off :
1) Double check the mechanical stuff : fan belt present and snug,
generator snug on mounts, wires firmly connected to generator, etc. You
should only be able to turn the generator fan with great difficulty, if
at all. If the generator has been off the car, it's worth repolarizing
it.
2) remove the wire from the 'F' terminal on the control box
(regulator). Measure the resistance between the F and D terminals, it
should be under 1 ohm. If not, the control box is bad.
3) Measure the resistance between the wire that came off the F terminal
and ground. It should be between 5 and 10 ohms. If not, either the
generator or (more likely) the wiring is bad.
Put the wires back, Start the engine, and set it for a fast idle
(1500-2000 rpm)
4) Terminal E to battery ground post should be under 1.0 volts. If not,
you have a bad ground. Also check from E to the generator housing.
5) Measure D to E. This should be around 13-15v, if it is then the
generator is working. Higher indicates a bad regulator.
6) Assuming D-E is under 13v, compare it with A-E. If they are the
same, the ignition lamp should be out. If not, the wiring to the lamp
is wrong.
7) Also assuming D-E is under 13v, check D-F. It should be under 1.0v,
if not, the regulator is bad or badly misadjusted. One exception to
this is if the ammeter is reading a lot of charge at this point, 15 amps
or more, which could indicate a bad or deeply discharged battery.
8) As a final check, (again assuming step 5 was under 13v) stop the
engine, remove both wires from the generator, jumper the terminals
together and connect the voltmeter from either terminal to ground.
Start the engine. Rev no higher than about 750 rpm, and check the
voltmeter reading. If you don't get at least 15v, the generator is
definitely bad. According to the book, around 4-8v indicates a bad
armature or brushes, around 1v indicates a bad field. If you do get
15v, reconnect the wires and repeat the test with the F and D wires at
the regulator. If you get different results here, then the wires are
bad.
9) If you get to this point, ask again <g>
Randall
"Freeman, Noah" wrote:
>
> Hello all...electrical prob (tr4) has me totally befuddled....
>
> Situation before any changes-
> -Blinkers working
> -blinker dash indicator working, but bulb in weird spot (dash
> replacement)
> -temp and fuel guages reading high for a months
> -then both temp and fuel guages reading 0 as of this morning, suddenly
> -generator light/amp guage working normally
>
> What I did (all at once)
> -changed bottom fuse in fuse box (35 amp) b/c it was blown (corrected
> zero reading temp/fuel guages)
> -Fiddled under dash, moved blinker bulb to correct spot, tried to make
> sense of comlete spaghetti under there
> -replaced voltage regulator with new unit
>
> What the new results are
> -fuel/temp guages reading correctly and exactly
> -blinkers blinking, but dash light not doing anything (weird)
> -generator light ALWAYS on, amp meter never going up to zero, always
> negative, getting less neg/dash light dimming at high revs...(even
> weirder)
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