QuestionI have a 88 Suburban. It has a 350, 4WD, and auto trans. I have had the alternator tested and that proved to be bad. I replaced the alternator, but the thing won't start. I have tested both the battery and starter and they are both good. I have tried jumping the battery, but no luck. When I turn the key to on, all of the lights will go on, but as soon as I turn the key to start, everything goes dead and the electrical gauge on the dash drops to zero. I am wondering if it could be the ignition switch. Is there any way to test that switch. Any help would be appreciated. Thank You.
AnswerHello Aaron,
Yes, it possibly could be the ignition switch, but there are some other possibilities also.
My first thought is a poor connection.
Start at the battery. If you have one of those batteries with both top and side connections, make sure any battery test you do is to the connections used by the truck, in this case, probably the side connections.
I have had those batteries where a load test to the top posts would show the battery to be great, but due to an internal bad connection, almost nothing would come out the side connections. You could measure 12 volts, and the lights would light, but it wouldn't crank, or carry even the headlights, and jumper cables did nothing unless they were connected directly to the cables.
That said, make sure the connections are clean, clean, clean inside, to bare metal, and tight.
Then check the other ends of both cables. On the starter, make sure the little alignment lug is in the proper place so the ring makes good connection. Then make sure the ground cable, where it bolts to the block is clean and tight.
Then back at the rear of the intake manifold, there is a ground strap to the firewall. Make sure it is connected, and yes...clean and tight.
Next there is a big connector through the firewall, where ALL the wires go into the cab, as well as coming back out through. Wiggle that and make sure it is tight. May even want to unplug it to see if there is any corrosion or melted wires in there.
Same on the ignition switch, as well as the neutral safety switch, both of which are on top of the steering column, above the drivers toes.
The neutral safety switch could keep it from cranking, but should have no effect on any lights, so it would be very low on my list.
You said all the lights go off...are we talking about all the lights that come on with the switch, or even the dome light and headlights? Turn the headlights on, and if they go off, or get real dim when you try to start, I would not suspect the ignition switch, but rather, the cables and things I mentioned earlier.
If they stay bright, then you are in the ign switch, firewall plug area.
Down at the starter, (I know it is almost impossible to even see, much less check), there are the two connections. The big battery post, and the small one with the wire from the ignition switch. You can use a jumper between those two wires,(First make sure the vehicle is in neutral!!), and the starter should crank, weather the ignition is on or off. May not start, but should crank the engine over. That will verify that the battery, and connections to the block and starter are good.
If it won't crank, make sure the small wire is connected to the proper small terminal. There may be a small terminal that isn't used.
If it is connected properly, and cranks when jumped, you are back at the switch and firewall plug.
There is a fusible link in the wire that supplies power to the ignition switch, and it could be blown, and just barely making contact. I believe it bolts onto the starter big battery post. Make sure you got it on, and it isn't just laying there against the post. It could be connected elsewhere, I'm not sure on the Burb.
This problem isn't going to be a problem with the connection to the instrument cluster, because the truck will run with that completely removed. Just a side thought.
Good luck,
Van
