Hello everyone,

I don't know where to turn so I figured I would turn to the expertise of our community.

I have a 1989 TII RX7 running a Microtech LT-10 EMS. The car has developed a strange voltage spike issue which I cannot figure out. While cruising, the voltage reads a healthy 14v. All of a sudden, the voltage will begin spiking up to 16v-17V and then returning to 14V. It seems to have a pattern of spiking every 10-12 seconds. When the voltage spikes, you can see the effects all throughout the car. Gauge cluster lights brighten, headlights, parking lights etc...

The alternator was swapped yesterday as well as a brand new optima yellow top battery. On my drive home yesterday, (Night time ofcourse) The voltage spiking began. The headlights went out (Can still open and close), my brake lights went out, and I had to resort to driving with my hazards which remained functional until I arrive home. My parking lights are still operational.

The other problem is that once this voltage spiking begins, the car has the tendency to idle very rough and will turn off if I do not keep the RPM's up. Needless to say, I had to shift into neutral, slow with the brakes, and then use the ebrake to stop while holding in the clutch and giving the car gas to stay alive at each and every light.

If there is anyone with any ideas, please help.

Thanks,

Erick

 

The alternator has a small plug on the back of it. One of these wires monitors the alternator output and uses that signal to Regulate the alternator. Either that wire is open or the alternator is corrupt internally.

 

Thanks for the information. I will check the alternator wires and post the results.

Thanks again,

Erick

 

Well, I got the chance to look at the wiring today. With the battery cables disconnected, I am getting a ground reading on the white-blue wire which leads to the 30 amp fuse in the main fuse block. If I disconnect the connector with the white-red wire which goes from the main fuse block to the internal fuse block the ground reading on the alternator wire goes away. When I reviewed the schem's I noticed that the white-blue wire from the alternator goes to the main fuse bock and that another white-blue wire goes to the main relay. When I inspected the car the connector which connects the white-blue wire tothe main fuse block has a red white wire sharing the same connector pin as the white-blue wire. Any ideas?