96 Suburban loses power when towing uphill

[crowingcat]

I tow a "light" tralier - 4,000 lbs - with my 96 GMC Suburban 1500 4wd 5.7L. When I get to a grade the transmission is slow to down shift and I lose all speed. I end going 25 mph in first gear. Any thoughts what causes this and what can be done to improve the situation? It has no problem pulling the trailer on flat ground.

 

[Molson02536]

I tow a "light" tralier - 4,000 lbs - with my 96 GMC Suburban 1500 4wd 5.7L. When I get to a grade the transmission is slow to down shift and I lose all speed. I end going 25 mph in first gear. Any thoughts what causes this and what can be done to improve the situation? It has no problem pulling the trailer on flat ground.

Inspect your TPS and the wire leads for smooth and linear electrical response over the entire range of motion. If not, replace.

Start with that and keep us posted.