Datsun Roadster Forum-311s.org

I am looking for some insight or advice. My ammeter gauge used to bounce or flicker above and below the zero center mark + or minus 5 degrees until I put in an in-line fuse from the starter (white wire). I used a 40 amp ATC fuse. The car starts and drives fine but now the ammeter doesn't seem to bounce any more. It stays pretty much right at the zero mark with no movement. I wasn't sure if I might have damaged the gauge some how so I hoooked up another gauge that I have as a back-up and it does the same thing, no movement. Is this a problem or is the in-line fuse acting as a noise filter? Just don't want to start melting my wiring harness. I burned up an ammeter once and the car wouldn't start. That was two years ago and I finally got around to putting in the in-line fuse. Thanks for any insight in advance.

With the ignition on and engine not running, turn on everything. Amp reading should fall. Turn off and gauge will go back to center. A really good battery and alternator won't draw much. Usually will waver with the turn signals or tapping brake light.

As long as the fuse is in series with the ammeter and not in parallel, it shouldn't affect it. You may have just fixed a bad connection without knowing it

I'd agree, but also go looking for that bad connection so you don't get stuck or have a fire!

Thanks guys,

I think I found the problem. I traced the wiring and found a bad connection with the black wire off the ammeter connecting to the fuse box. The wire had pretty much pulled away from the connector. Replaced that and the gauge came right back. Not sure how that could have happened. might have pulled on the wiring some how when I replaced my cowl drain hose this last weekend. Anyway, now when the lights are turned on the gauge drops into the negative range with the engine off. Seems to be working fine again. Thanks for your help.

Can you give some details on how and where you added the fuse? I'd like to do the same on my car.

Thanks!

I actually added two (2) in-line fuses; one between the starter and the ammeter and one coming from the alternator. Both wires are under the hood and are both WHITE wires on my car. I used ATC fuse holders with rubber caps and 35 amp fuses. Make sure to disconnect the negative battery cable first. Tha's about it really. There might be better ways but I went for the simpliest route.

That pretty much covers it. You may consider putting a 30 or even a 25 after the gauge in order to save the it in the event of a direct short. I think there is a tech article on this in the main site?

TR