P0700 code on 2019 Tahoe

Jcand32022 · May 29, 2024

We went camping this weekend and towed our camper no problem to the site and back to storage. Everything worked fine trans temp stayed around 185 peaked at 200 when in traffic and on a steeper climb. After dropping off at the storage facility I got on the highway. Lost power at about 75 mph car was in limp mode for about 30 seconds while I pulled over then came back to normal but the CEL came on. I did a scan and got a P0700 code as well as a low voltage fuel pump code. I spoke to a friend who is a mechanic and he advised it is the beginning of needing a new transmission. I'm hoping it was just a fluke or something off after towing and different driving conditions. But that may just be wishful thinking

Big Mama · May 30, 2024

How many miles are on your rig? Unfortunately these are known to have TC and transmission issues but that doesn’t mean that your issue. Guys with more experience with your rig will chime in.

NickTransmissions · May 30, 2024

Jcand32022 said:
We went camping this weekend and towed our camper no problem to the site and back to storage. Everything worked fine trans temp stayed around 185 peaked at 200 when in traffic and on a steeper climb. After dropping off at the storage facility I got on the highway. Lost power at about 75 mph car was in limp mode for about 30 seconds while I pulled over then came back to normal but the CEL came on. I did a scan and got a P0700 code as well as a low voltage fuel pump code. I spoke to a friend who is a mechanic and he advised it is the beginning of needing a new transmission. I'm hoping it was just a fluke or something off after towing and different driving conditions. But that may just be wishful thinking

Not sure if you've figured this out already but if not, take the vehicle for a drive with a two way scan tool plugged in and live transmission and torque converter data displayed. You want to monitor things like tcc slip speeds at 70% or higher tcc duty cycle (should be no more than 10 rpm or so), shift speeds, shift command and response, etc.

Also, id look for any issues with wiring, including damaged or missing grounds anywhere on the vehicle, particularly around the fuel pump. Do a fuel prrssure test to see if pump is weak/failing.

Let us know what you find.

Jcand32022 · Jun 14, 2024

Big Mama said:
How many miles are on your rig? Unfortunately these are known to have TC and transmission issues but that doesn’t mean that your issue. Guys with more experience with your rig will chime in.

108k but maintenance had been kept up

B-train · Jun 14, 2024

What transmission?

I've had that code show up randomly on my wife's yukon as well in the last couple months. 2017 Denali with the 8 speed, 152k.

I'll be curious to see what you find. The CEL has come on and off at random. Truck runs and drives fine. I'm just trying to keep an eye on it and see if there is a particular event that triggers it. I'm preparing for the inevitable possibility that it's a failing transmission. I'm sure running the pump low on fluid for a number of miles after the last dealership service hasn't helped anything........

Good luck on yours.

Jcand32022 · Jun 15, 2024

Jcand32022 said:
We went camping this weekend and towed our camper no problem to the site and back to storage. Everything worked fine trans temp stayed around 185 peaked at 200 when in traffic and on a steeper climb. After dropping off at the storage facility I got on the highway. Lost power at about 75 mph car was in limp mode for about 30 seconds while I pulled over then came back to normal but the CEL came on. I did a scan and got a P0700 code as well as a low voltage fuel pump code. I spoke to a friend who is a mechanic and he advised it is the beginning of needing a new transmission. I'm hoping it was just a fluke or something off after towing and different driving conditions. But that may just be wishful thinking

So still trying to figure out the issue. Now it appears I have some sort of intermittent electrical issue l, getting both high and low voltage reading and the BCM had lost connection. Going to go back to shop in a couple weeks for a better diagnosis

P0700 code on 2019 Tahoe

Jcand32022

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Big Mama

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NickTransmissions

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