The Stovebolt Site Forums The Parking Lot '60-'66 Trucks Converting to Ammeter Gauge "what the....."

'Evenin:
Allow me to start out with an acknowledgement of appreciation for this site and all those involved, Super!

Though I've been a member for a few months (and learned a bunch) this is my inaugural post (pics and full story posting @ 11). I ran several searches to no avail so here goes...

I just swapped to full gauges out of a '62 60 series firetruck (great donor vehicle for gauges, they look new) to my 235/SM420 equipped '60 Apache 10 short fleet and caused issue(s):

1) The ammeter swings to full Discharge when I signal a turn (and never really centers like it should) Gen/batt/wires/grounds are all known good and worked fine 15 min prior before I swapped. My shop manual does show slight variances in wire color as well as the ammeter gauge wires bypassing ignition unlike the telltale schematic. I believe this is so to do safety systems check @ startup on the telltale but maybe there's a wiring mod associated with this swap?

2) Gets better, the engine will not shut off when the ignition key is turned off. Again, this only happens when I run the full gauge IP, works fine when I replace with the orig telltale IP.

Seemingly unrelated events but I'm betting since I was careful to not monkey with any other variables, they are related and sure hope someone can ring in with an assist.

Much Obliged in Advance!

In the meantime, this an opportunity to go blow some cobwebs out of one of my 4 speed Olds Starfire convertibles, I'll be right back...

The engine continues to run because you have one of the ammeter leads connected to an ignition source and one to a B+ source.
One lead must be very close to the alternator output stud and the other lead must be closer to the battery positive so that the meter can sense the voltage potential and indicate charge vs discharge.

RWD:
Interesting.
Earlier today, I proved out a hunch in that the problem (engine stop/ no stop) phenomenom does indeed relate to the ammeter as you mentioned. Simply disconnecting the ammeter makes the problem go away. Alas, reconnecting brings it right back.

OK, so as I re-read your response, is this simply a wire routing issue or indeed a miswire? And I apologize in advance if the answer is obvious, electricity/schematics/amps/volts never one of my strong suits. However, perserverance/stubborness is so eventually my dimbulb will click on! And besides, a bad day spent wrenching still beats a good day at the office.

Wire routing isn't right obviously. I believe the original truck's wiring had one lead near the alt/gen output and one lead near the battery pos lead, at or near the horn relay. Both wires need to be connected to B+, as in "hot all the time" circuits, not ignition switched. One wire must be close to the alt/gen output wire and the other wire must be closer to the battery positive, such as at the horn relay. On my '63 I have an '03 5.3L installed, so I rewired the whole truck and don't remember exacly how the original set-up was, but the amp gauge will function properly if you connect the leads as described above. If you get them backwards, you'll know it because the amp gauge will deflect to the discharge side when the alt is charging. If this occurs, simply reverse the leads to the gauge. On my truck I have the alternator sense wire connected directly to the alt output stud and the battery load sense wire connected to a battery fed fuse in the IP fuse block. Remember, both wires must be connected to B+ circuits to avoid the feedback issue that was not allowing you to shut the engine off.

RWD:
Spot On!
Per your suggestion, I wired the ammeter stand alone to Batt + and Batt + voltage reg (shop manual schematic for "shunt type" ammeter and have repeatably secured the following:

1) An ammeter (and charging system) that appears to be fully functional or "normal".

2) A truck that shuts off when you turn the key off.


Both good reasons/ excuses to go for a ride.

Very Much Obliged!