We have a 1988 Silverado 5.7 V8 -when we turn on the headlights we lose power...?

Question

We have had the battery and alternator checked- both good. Also, anything plugged into the cigg lighter drains power and when we turn the turn signals on you we can see the voltage meter go up and down. Does anyone know what is causing this? Any help is appreciated.

Answer 1

You have a bad ground wire between the engine and the frame. The battery and alternator are grounded to the engine, but everything else is grounded to the frame. So, if you don't have a good connection between the two, your voltages go all over the place.

Answer 2

loose or dirty main power connections in the main junction box on the firewall on the passenger side of the engine compartment.under the black plastic cover. Also check the ground connections on the engine for the battery and the pcm grounds on the intake. there is also a ground strap located on the passenger side under the ac box that corrodes and breaks off the engine side. Don't forget to check the actual battery cables for corrsion @ the battery.
Last thing to check is for a faulty ignition switch electrical which do fail and cause similar symptoms as you discribed.

Answer 3

The wiring harness where it goes in to the fire wall below the master cylinder is where the problem is. You will need to check this plugin and repair. If this is not bad then check the grounds from the engine to the frame or body of the car.

Answer 4

Check the battery connecton at the starter as the charge wire may be loose,also check that all the positive connections are clean as well as all the grounds at the cables.there are smaller wires for the engine to the firewall and frame that need to be tight and clean

Answer 5

It could be a voltage regulator or faulty wiring