I was doubled checking the lead seals on my crossover when I noticed a braided wire ground that was attached to the top of the passenger side frame rail just hanging into the wheel well. What does it go to?


Looking at the ring it has just recently come off and the only thing I have messed with was the exhuast. Could that ground possibly have been grounding to the exhaust manifold? It would make sense that the frame rails ground to the block, but I have never even seen any braided wire attached to this block and I dont think it will reach the lower rear intake runner stud where the PCM grounds...


If someone with a k series truck could check to see where their ground goes from that frame rail on it would be awsome.


Thanks in advance!

That is the third most important ground on the truck. It grounds the ECM wire harness where it emerges from the firewall under the a/c dryer and behind the turbo, next to where the heater hoses go to the heater core. The braided cable is inadequite as it corrodes and gets dirty. I sodered connectors on the ends of a 6 guage sheathed copper strand and installed it on mine.

I found the area where the ECM wire harness passes through the firewall. Since you upgraded yours, Ill do the same, however where exactly does it ground on this harness? Is there a wire in the harness that the ring terminal bolts to, or does the wireharness ground to the firewall and this braided wire connect that firewall ground to the frame ground?

If you look toward the driverside there's a threaded stud coming out through the firewall with that bundle. It it the grounding stud for the ECM itself, very important!! If the ecm can't ground it causes gremlins to emerge, this is an EFI controlled engine. Without the E you get no FI.

That is the body to chassis ground link - lighting, accessories, horns, etc - anything that uses the body for ground return.


PCM grounds are all thru the stud at the passenger-side rear of the intake manifold.


FSD\PMD and Fuel Solenoid ground is the black wire top rear on the Inj Pump.


PCM ground return to the battery(s) is thru the engine block - very important to maintain clean connections to and from the engine block.

Any idea what size and thread that stud is? Im guessing 8mm coarse thread? Im going to have to buy a nut/lockwasher/washer to reachnor it tomorrow.


qm - the proper stud is about 1" to the drivers side and about 2" below it?


I need to finish up with the 1/0 grounding upgrades, Im tired of the wierd voltage swings on this truck...lol

Inspect, clean and tighten the four connectors on the two batteries. A bad connection here will give you voltage spikes.

already done that 2x now....lol


Any idea on the size of that stud?Edited by: Bumpin' Yota

It is your primary connection and the GM connectors are a weak link. I switched to top posts and I have replaced most of those plastic covered terminals already on my three trucks. Both of the negatives on the batteries go to either side of the top intake manifold.


http://www.dieselplace.com/forum/uploads/quantummechanic/2004-11-07_061629_batts.jpgEdited by: quantum mechanic

Well I pulled out the coolant resevoir, air box, and the PS battery for ample working room and dug in....


I found the correct stud (not what I was origionally looking at) and discovered that the engine block to firewall ground was on this stud and was VERY loose. So I reinstalled the firewall to chassis ground, then added a 4ga run from that ground point to the PS battery. Torqued it down good and tight and reinstalled everything.


TAAADAAAH! The voltage gauge on the dash now reads much closer to what the alt is charging them to!


What burns me is that the AC shop must have disconnected that ground for God-knows-what reason, then forgot about it! And then only finger tightened the nut anchoring the block-to-firewall ground thus leaving the firewall-to-chassis ground to go exploring the lower exhuast system.....