Erratic Intermittent Electrical Issue

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RevIT

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I have a 2007 Suburban LTZ with 210,000+ miles on it. Four months ago the dash lights and gauges started flashing and jumping all over and the door locks were randomly clicking. I had replaced the battery and alternator a few months earlier, but I replaced the alternator again and then verified both are OK off the vehicle. I have replaced the ground cables from the battery, added a ground cable from the firewall to the alternator bracket, and from the body to frame at the driver's rear corner. The new grounds seemed to do the trick until yesterday. Same thing happened, and then it wouldn't start. The lights would come on, but when I turned the key to the start position all the lights go out and it won't crank. The code reader wouldn't connect to the system. I removed the positive cable for a few minutes (just because it is easier to get to than the ground!) and when I put it back on it started. I had codes U0073 and P0700, but it would start. It seemed to be in a limp-in mode, so I cleared the codes and it ran great for the afternoon. This morning, same crazy thing: dash warning lights all flashing on and off, warnings about stabilitrack and four wheel drive systems, hard shifting, lower than normal power (limp in mode?), door lock switches activating randomly, and lots of clicking under the dash. I'm not able to get the coder reader to connect to find codes, and it won't start now that I'm at work. (At least I grabbed a few tools and my coveralls before leaving home, so I'll hopefully be able to reset it and drive home.)

I live in northern WI and the truck spent a few years in Upper MI, so it does have lots of rust underneath, and I've had to replace a few wires that got corroded. I'm guessing I have a bad connection, some corrosion, a cracked wire, or a combination of those. Any help as to what color wires to look at or where possible connections are for me to look first would be greatly appreciated!
 

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Not sure if you have the two ground connections that are underneath the body (under the driver's side front seat), just aft of the wheel well, but those get rusted up and can cause issues. There should be two ground bolts there and those need to be in good shape. Since your other ground connections seemed to fix things, I'd probably also revisit those and clean and tighten them.
 
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RevIT

RevIT

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Not sure if you have the two ground connections that are underneath the body (under the driver's side front seat), just aft of the wheel well, but those get rusted up and can cause issues. There should be two ground bolts there and those need to be in good shape. Since your other ground connections seemed to fix things, I'd probably also revisit those and clean and tighten them.[/QUOTE

I do remember finding one in that location, and it was in good shape.

I found the connector to the air-ride suspension bypass module mounted above the spare tire was covered with corrosion. (I replaced the air suspension with an Arnott conversion kit just over a year ago). I guess their connector isn't designed for external use! It tripped the codes when I wiggled the wires, so I'm guessing that's the culprit. I'm contacting the supplier today to see about getting a new connector, testing the module and sealing the new connector the way it should have been. Hope this corrects the problem!
 
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RevIT

RevIT

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Contacted Arnott and they are sending a new module under warranty! They now have a module that connects under the dash, protected from the elements. I removed the old module and everything works fine except one suspension error. Hopefully that error message goes away once I get the new module and install it. Still less expensive than replacing all the air shocks, compressor and whatever else had gotten rusted out.ArnottModuleCorroded.jpg
 

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On my 02, I went through a few of Arnotts bypass modules because they kept failing and there was no corrosion, just ****** modules. I finally wired in resistors. No problem since.
 

Denali207

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I have a 2007 Suburban LTZ with 210,000+ miles on it. Four months ago the dash lights and gauges started flashing and jumping all over and the door locks were randomly clicking. I had replaced the battery and alternator a few months earlier, but I replaced the alternator again and then verified both are OK off the vehicle. I have replaced the ground cables from the battery, added a ground cable from the firewall to the alternator bracket, and from the body to frame at the driver's rear corner. The new grounds seemed to do the trick until yesterday. Same thing happened, and then it wouldn't start. The lights would come on, but when I turned the key to the start position all the lights go out and it won't crank. The code reader wouldn't connect to the system. I removed the positive cable for a few minutes (just because it is easier to get to than the ground!) and when I put it back on it started. I had codes U0073 and P0700, but it would start. It seemed to be in a limp-in mode, so I cleared the codes and it ran great for the afternoon. This morning, same crazy thing: dash warning lights all flashing on and off, warnings about stabilitrack and four wheel drive systems, hard shifting, lower than normal power (limp in mode?), door lock switches activating randomly, and lots of clicking under the dash. I'm not able to get the coder reader to connect to find codes, and it won't start now that I'm at work. (At least I grabbed a few tools and my coveralls before leaving home, so I'll hopefully be able to reset it and drive home.)

I live in northern WI and the truck spent a few years in Upper MI, so it does have lots of rust underneath, and I've had to replace a few wires that got corroded. I'm guessing I have a bad connection, some corrosion, a cracked wire, or a combination of those. Any help as to what color wires to look at or where possible connections are for me to look first would be greatly appreciated!
I’m currently experiencing the exact same issue with my 2007 Denali Yukon. I’m wondering if you ever solved your issue!
 

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