Sorry to keep bothering you but this morning I was doing about 80 kilometers per hour and I hit the tow/haul button. I was on a fairly flat stretch of road and the engine went from 16k rpm to 22k rpm, I hit the button again and it went back to 16k rpm. It doesn't do this all the time, also I replaced the transfercase switch on friday, 4lo light still flashes, the rest work. Any ideas? Thank you very much for your time. I am going to do the fuel pressure test, as soon as I buy a fuel pressure tester.

 

Well it sounds normal. Using tow haul mode raises the shift points. So your overdrive will shift no earlier than 100km per hour. Any less and it will kick down to 3rd or drive.

 

according to a handy dandy internet conversion, i see you were running around 50 mph. which means tow haul a) unlocked your torque converter and b) might've downshifted. completely normal. as for the transfer case, im gonna need some more information on your truck.

 

Thanks for your input, my truck is a 2000 Silverado, 320,000 kilometres on it(almost 200k miles), 6 litre, 4X4, 2500 LT. I just changed the 4 wheel drive switch on the dashboard. I am just wondering why the truck shakes while going uphill until I either give more gas or I push the tow/haul button. There are no codes being thrown, I have replaced the plugs, checked the ohms on the plug wires. I have been told I should change the transfer case fluid, flush it and fill it again and put some Lucas Oil additive in with it. Thanks again.

 

For the 4x4 dash light....

The reason is probably that the transfer case isn't engaged completly. Espically if yours is shifted electrically rather than manually.

I have had several electrically shifted transer cases in the Ford Bronco II vehicles which have the same problem. And in those it was the transfer case that wasn't completly engaged, What I did to remedy this was to shift into high range by pushing the high range buttion (on mine it had two buttions... One was for the 4x4 hugh range and the other was for 4x4 low range). Then once the transfer case had shifted I would either drive forword or backward just a bit to make sure the transfer case was completly engaged. This always worked for me anyhow. You can try this too... It may just solve your problem as well.

Otherwise you may have to check into it a little further and see what is going on underneith. If you have the electrically shifted model then you will see a motor that is mounted to the rear of the transfer cxase. You can also try unpluging and then repluging it back in. Sometimes this also helps too. I had to do this on my Bronco II for the low range.

Another thing to consider would be maybe you have a relay or a sensor that is going bad as well. Or maybe even the motoe that shifts the transfer case from high to low is going bad as well.

Hope this helps you some.

P.S. In regards to your shaking under load....it may be not be the case but I had a buddy whos truck would shake like yours and his problem ended up being a broken motor mount.

 

are you in neutral and almost stopped when you try to hit 4lo?

 

I am completely stopped. I have figured out that I have to be in neutral, then it will go into 4lo