'04 Silverado transmission slip

Chevygrl · January 29, 2017

I drive a 2004 Silverado 4wd with the 4.8lt. a few months back I developed a slip and it's been a uphill battle trying to figure out the cause so I'm turning to all you guys.

I had the original transmission rebuilt to no avail. Replaced solenoids, replaced the valve body. Nothing helped, so I went ahead and bought another transmission. This transmission is doing the same thing and my truck is pretty much stuck in constant limp mode. This weekend I had the harness replaced running from the exterior of the transmission to the ECM and TCM. And it was okay for the first few minutes and now it's back to square one.

Please help, my mind is blank any suggestions would be extremely appreciated. I've had it at my local dealership already they are lost on it they were who suggested the harness but nothing has worked this far.

GMCustomerService · February 1, 2017

Hi Chevygrl,

We’re sorry to hear that you’re experiencing this concern with your Silverado. If you would like for us to look into this further, and reach out to your dealerships, please let us know in a private message! Be sure to include your VIN, current mileage, contact information and dealers name.

Bret B.

GM Customer Care

Daryl LBZ · February 1, 2017

Has anything be done with the torque converter?

Chevygrl · February 1, 2017

The torque converter was replaced when I rebuilt the transmission.

It's Tim · February 1, 2017

Slips in all gears, only during shifts, when exactly? Are you sure it's a transmission and not an engine issue?

Chevygrl · February 1, 2017

At first it was 2-3 when I had it rebuilt, the rebuild or a replacement was suggested by dealership. After the rebuild made no difference I decided to fully replace the trans. Now with a Remanufactured GM transmission in there it's just gone into full limp mode and nobody can tell me why. I've had it at the dealership they hooked it up scanned my computers said the only thing they saw was a large power surge that may have caused damage to a circuit or harness they then suggested the harness I had replaced this past weekend and it worked for a few minutes then went right back to limp mode. Which has me pretty convinced it's electrical.

Duelin · February 2, 2017

Have you had any aftermarket electrical accessories installed? I had a friend that had 4 transmission installed before he found out that the aftermarket alarm & remote start installation was causing the problem.

Good Luck

Chevygrl · February 2, 2017

No the only thing has been the radio the person had in there before which was one of those touch screen ones DVD player and all which shorted out and was sucking up power so I took it out but I fear not before it damaged something in there.

I discussed it yesterday with my guy at the dealership, I questioned him on everything that's on the same circuit as that harness which is everything from wheel speed sensors to 02 sensors and sensors in the dashboard. So I'm going to start one by one replacing them all and see what happens from there.

It's Tim · February 2, 2017

I would start with checking all the fuse and possibly start with swapping in a TCM from the boneyard.

Chevygrl · February 3, 2017

Tried the TCM already but we're going to go over all fuses and sensors again and do a complete tune up and see what happens. If not I'm lost on it and Ironhide may get traded in