2003 Suburuban Electrical Shutoff when hitting bump

[pastorbennie]

When I hit a bump in the road, does not have to be severe, the entire electrical system seems to reset. All gauges go out and come back on. ABS light comes on until the vehicle is restarted. It acts like there is a loose ground but I can not find the ground. The vehicle runs rough for a while after the reset. This seems to indicate that the OBD is reset and needs several driving cycles to run right. HELP any similar problems?

[klinn]

I have seen a few ignition switches cause this type of thing. The switch design has been changed, and it is a different color. The new one has a grey back on it, the origional ones had a black. You might see if some of the other electrical accessories act up when you see the gauges reset. Not to moslead you either, but the cluster grounds are not known for coming loose. I would just make sure you aren't seeing a voltage loss due to an ignition switch. However, a loose ground could cause this also, make sure the battery connections are tight. Hope this helps.

[MT-2500]

After looking it over good and if it still does it.
Hook a volt meter or test light up to some of the main power feeds and see if you can find the lose of power.
Double check the battery cables and post.
Good luck and let us know how it goes.
MT

[pastorbennie]

I had not thought about the ignition switch. Just to clarify, when I get this glitch, it is pretty much like disconnecting the battery for a millisecond. It is not long enough to lose power to the engine or even for the radio to default. I will look into the switch. Is there a maintenance bulletin I can reference for the trouble shooting or repair? Finally, I do not have a repair manual and I cannot seem to locate all of the grounds. Thanks for the replies.

[pastorbennie]

It is getting worse... Still can not pin point the issue... Explain what you mean by a black back?

[klinn]

The ignition switch has a cover on the end, the original ones has a black cover on the end, the replacement has a gray cover on the end. It was guess, but a thought. The statement about the ABS light might mave something to do with it. If you crawl under the truck, the second body mount on the driver side has a couple of grounds. Sometimes some excessive undercoating could cause a poor connection at times. Mostly I have only seen this related to an ABS light on only, and not all you describe, but since you mentioned an ABS light, thought I'd mention it. Just to clarify, the first body mount is up by the radiator, the second is about where the drivers door hinges area. There is most likely two eyelets with three or four wires. They are connected with a bolt into the frame. Remove the bolt, clean the frame (down to the metal for good connection) and eyelets. Reassemble and see if it helps. After you do so, I would recommend getting some spray rubberized undercoating (get at most auto parts stores) and covering the bare metal exposed from cleaning, but spraying down after you completely reassemble the wires. It will not hurt the wiring. Other than that, I can't think of much. Has there been any work done in the near past, and now you are having this problem? Any other things noticed? Like, other lights not working, door locks not working, etc.

[pastorbennie]

I do have the old switch... I had not been able to locate the second ground. I will check it and see what happens. there has been no work done on the vehcile... I will let you guys no as soon as I resolve the issue. thanks for the help...