Transmission Ground Strap?

[Caman96]

The trans shop I used for my '88 K1500 700 trans, and the Sonoma 4L60E, always adds a ground strap from trans to frame.

I figure it can't hurt. Probably does no good other than profit enhancement

Just noticed this post. That’s where I read that, it was in your post where you mentioned a recent transmission rebuild.

 

[Caman96]

I’m adding “transmission-frame, ground strap”

??? Do you mean from the support member/with trans. mount to frame.

 

[Orpedcrow]

??? Do you mean from the support member/with trans. mount to frame.

I’ll probably do something like the tail shaft to the cross member. Basically bypassing the rubber mount.

 

[someotherguy]

I've seen where an engine ground was missing and the negative cable was bolted to just a frame. The truck (late 70s Ford) was killing alternators and having slow cranking when hot. The entire drivetrain was grounded through the driveshaft to the rear end and back up through the parking brake cable. I was surprised that the Neverspark ignition system didn't croak.

Have seen 'em melt a shifter cable on older vehicles due to poor grounds, too. That power will find a path to ground.

Richard

 

[1998_K1500_Sub]

Is there a dedicated transmission ground strap or is it something that’s just incorporated into its harness? Read something recently where a builder also added an additional to all his rebuilds.

I'm quite certain all the "grounds" for the transmission control and sensors are via separate ground leads to the ECU; no "ground path" through the case and engine block is necessary or desired.

I say "I'm quite certain" because (a) that would be the better design and (b) that's how GM generally constructs their ground paths between the ECU and their related devices.

Similarly, the "grounds" in the transmission which are related to ECU circuits are isolated from any transmission case / engine block ground, e.g., as is done for the fuel injectors, TPS, IAC, and EGR devices, just to name some examples.

So, no talk about "ground straps" to the transmission or such, at least for ECU control circuits

 

[Caman96]

I'm quite certain all the "grounds" for the transmission control and sensors are via separate ground leads to the ECU; no "ground path" through the case and engine block is necessary or desired.

I say "I'm quite certain" because (a) that would be the better design and (b) that's how GM generally constructs their ground paths between the ECU and their related devices.

So, no talk about "ground straps" to the transmission or such

Yeah, but there was talk of it, which is why I asked. @Schurkey had mentioned it in one of his posts. Also @Orpedcrow mentioned adding one. I climbed under and don’t even see where one could be added. But, definitely no exterior factory strap.

 

[1998_K1500_Sub]

Yeah, but there was talk of it, which is why I asked. @Schurkey had mentioned it in one of his posts. I climbed under and don’t even see where one could be added.

Such a design may have dated back to the 70s-era, when no ECU was involved.

I seem to remember seeing solitary connector on the TH400s of that time... to trigger the kickdown, e.g., off the corresponding switch that was triggered by WOT throttle position(?)

 

[Caman96]

I came across this earlier. Seems they were on a TH350.

Transmission Ground strap & detent cable

I just installed my new TCI TH350. It came with a ground strap on the tail cone. Where would you put this to? It's only about 8" long. Also I put a brand new detent cable in and it seems the hole for it in the trans is bigger than the detents shaft. I tightened it down pretty tight but I still...

nastyz28.com

 

[1998_K1500_Sub]

I came across this earlier. Seems they were on a TH350.

Transmission Ground strap & detent cable

I just installed my new TCI TH350. It came with a ground strap on the tail cone. Where would you put this to? It's only about 8" long. Also I put a brand new detent cable in and it seems the hole for it in the trans is bigger than the detents shaft. I tightened it down pretty tight but I still...

nastyz28.com

^^^ yeah, on TCI's TH350s anyway. Leaves one wondering "Why?"... maybe if it had a lockup TC, e.g., early 700R4s would have grounded the TCC solenoid through the case to the engine block for ground, and I know some TH350s had lockup provisions. Just a guess.

I might peruse a GM service manual to see if (why) the OEM did such things.

(edit) At the link you provided, someone posted this:

"No ground strap will cause glazing of the clutches in an auto trans."

WTF is with that? I wonder if the guy was mis-applying some knowledge he gained elsewhere which was applicable to another, different situation.

 

[1998_K1500_Sub]

I don’t see an advantage of grounding the case. the grounds for the sensors and solenoids should be in the harness.

This jibes with the GM design, so "yeah".

I’m adding “transmission-frame, ground strap” to my list of things to do. Might not help, but it won’t hurt.

Notice that GM uses a star ground design on the GMT400 and I suspect most of their modern vehicles, and there's a reason.

Dropping random, additional grounds into an existing design is... a gamble. The resulting ground paths can turn out to be a bad thing... not always, but perhaps, and so best avoided.

Augmenting / maintaining the existing ground layout is the better approach.

If someone really wants to add a transmission case ground strap, add it between the case and the engine block. I wouldn't suggest it, but what do I know