GT ammeter light

[opelspyder]

On the current GT I am restoring the ammeter charge light does not come on when I turn the key on, but I believe it did come on when I first tested lights. Which wire actually powers the light, the light blue and white wire or one off the gauge. I want to troubleshoot by testing with the dash in, before I have to pull it all back out to change a bulb or something else.
Thanks
Keith

[markandson]

Light Blue w/White Stripe goes to dash light

[tekenaar]

Originally Posted by markandson Light Blue w/White Stripe goes to dash light

. . . other end goes to the regulator B+ red wire!

[opelspyder]

Okay so when key is on, I should have 12v at the red wire to the D+ of the voltage regulator connector. If not, I have a problem there. If I do, then I will check the wire past the fusible link. If I have power there, then I may figure pulling the dash as I have a bad ground, or a burned out light. Anyone see anything I might be missing before I try???
Keith

[namba209]

Keith, a little primer on how that system works. With the key on, power to the lite comes from the Red/Black wire terminal block between the speedo and Amp/Oil gage, which also powers the fuel and temp gages, the brake fail lite and powers the tach. The other side of the bulb is grounded through the Lt Blue/White wire attached at the fusible link on the plug at the regulator, which goes to the D+ wire to the alternator. As the voltage generated by the alternator comes up, the voltage differential becomes neutral and the lite turns off. A quick and dirty way to check the bulb out, is to look for continuity at the instrument panel connectors, with the key off, Black, Pin #1 and Yellow, Pin #6. It may not show all zeros on an ohmmeter due to the bulbs resistance, but it may tell you if the bulb is good or not, or if there is a good connection at the terminal block. With the key on, check for voltage at the Black connector, Pin #1 and ground, then you'll know if the Black/Red wire has power to it, at least as far as the terminal block. Or you can check it out at fuse #6. Also, to see is there is a ground through the alternator, check Yellow connector, Pin #6 to ground for continuity. One thing to remember, if the ammeter light is burned out, there will be no output from the alternator. HTH.