2 replies to this topic

[Ryan Roberson]

At first, it was only at high RPM.  Noticed it on the first outing with the car after the car hit the wall at Gateway a month ago.  I had a multimeter at the track, and it looked like it was over-charging, so I changed the alternator on Sunday morning.  Went out for the warmup, and the light still came on, although now it wasn't limited to high-rpm.  Checked the output with a multimeter, and it didn't look like it was under or overcharging.

 

Yesterday, I added the voltmeter so I could see what was going on.  And I replaced the battery and the kill switch.  I cleaned the three main grounds, and checked the alternator wire harness all the way to the back of the engine.

 

Most of the time the alt outputs right where I think it should (14.1 to 14.9), but as it warms up, I start getting the charge lamp on the dash, and some spikes indicated on the voltmeter.  FWIW, the charge lamp doesn't seem to correspond to anything, in particular, happening with the voltage as indicated at the voltmeter.

 

Any ideas?

 

Here's some video of what's happening (voltmeter is the gauge at the bottom of the console, green is anything between 13.9 and 15.9V; outside that range, the gauge is red).  Note the charge lamp on the dash too.

 

Thanks in advance!  I hate electrical gremlins.......

 

http://youtu.be/oPYnhGSdq_M

 

 

1990 Miata

 

[RazerX]

Check your harness plugs in the back of the instrument cluster and/or borrow another cluster.  A large impact and the cluster can short against other objects (dash roll bar).   

[Ryan Roberson]

Got it.  I'll give it a shot.  Thx.