Intermittent loss of electrical power

[Edahall]

I've got an 82 Suburban with the 6.2 diesel. Sometimes, when I go to start the engine, the glow plugs don't activate. However, if I just momentarily run the starter, the glow plugs will activate. Then there are other times when I loose total power in the whole vehicle and nothing works including the starter, glow plugs, radio and cigarette lighter. I haven't checked if the head lights also quit working. Sometimes, if I move the shifter back and forth, it'll start. Other times, that also doesn't work so if I open the hood and give it a big slam, then it'll start. This is getting frustrating and I'm afraid it will leave me stranded soon. Any ideas on what the problem is? Thanks

[DmaxMaverick]

Poor ground(s) and/or battery terminal contact. Could also be the ignition switch (much less common). It's an old issue, and requires an old solution....Elbow grease.

Even if the terminals look good, they can be making poor contact. Check the cable inside the insulation for green/white stuff near the terminals. If you have it, the cable needs to be replaced.

[Edahall]

Thanks for the reply. I replaced the ignition switch and I thought it fixed the problem but it seems to be creeping back again. I'm going to check the grounds. I noticed that the strap that goes from the engine block to the firewall on the passenger side is missing.

[DmaxMaverick]

That bonding strap from the engine to the firewall is critical. It relieves the ground load from other incidental locations, which can/will fail over time. Also check/clean the connection from the batt- to frame, and the batt+ to starter solenoid lug. You also have a fusible link from the solenoid lug to ACC power, which can be intermittent before it blows (fat piece in the wire). If the fusible link is brittle or cracked (crystallized/burned), it's on its way out. They can be replaced with another fusible link, or a Maxi-Fuse socket (50-100 amps, depending on acc. needs).

[Edahall]

Thanks for the reply. Last night I went and reconnected the grounding strap. The screw had fallen out due to the hole being stripped. I then went and tightened all 3 grounds. 2 grounds go to the frame and the other goes to the power steering pump bracket. I also removed and reconnected the big fuse panel plugin. So far there have been no issues but I'll need several more days before my confidence level is restored.

[DmaxMaverick]

Good luck. It's certainly not the solution every time, but it's more common than any other. With a missing, and several loose grounds, it sure doesn't hurt to clean up your electrical picture.

[Edahall]

Also check/clean the connection from the batt- to frame, and the batt+ to starter solenoid lug.

Problem is fixed. I'm almost 100% sure the above suggestion was the problem. Addressing the grounds seemed to improve the situation but the problem crept back up again so I went to the next step and cleaned those connections that go to the starter solenoid. They were badly corroded so I got them cleaned and put them back on and now it starts like it should.