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Discussion Starter · #1 ·
Hello: Thank you for taking a look at my post. There is a lot here to unravel, but I wonder if 2 of the three things are related.
First:
I have a 1998 K2500 Suburban: It was a 454 with 4:10 gears.
It is lifted 4".
It has a new 400 SBC, dart block, edelbrock heads and intake, 385 hp, 465 torque Max on each. Fast EFI 1.0
New Monster Transmission and Transfer case. TCI transmission controller.
New 4x4 dash switch, new Transfer case motor, New Transfer case actuator. ( All electronic) New neutral safety switch.
4 hi works fine, 2 hi works fine. 4 lo will not go even start to go in. I believe it is not reading the neutral position when I try to engage it.
Is there something other than the neutral safety switch that tells the transfer case that the truck is in neutral?
Can I by pass any of this?
How do I find the neutral wire that lets 4 lo engage. Or is it in the old harness or CPU?

Second:
Original tires were 28", I now have 34". The suggested gearing according to the formula to get similar performance says 4.88 gears should be installed. Is this too much for highway or is this correct. I will be hauling a camper trailer that weighs 5,300 pounds plus gear.

Third:
This new Monster transmission: is Slipping in hot weather, or at least that is what happened the to last times I drove it. It was 97 degrees I drove 45 minutes then headed back. The trans slipped when it down shifted, RPM spiked. I let off and coasted, Felt it re-engage, I drove it for 5 minutes, it did it again. I let it set for 15 minutes, took off again ran for 15 twenty minutes slipped again. pulled over again. Then after a wait started out again. the temp. out side dropped to 92 and it was starting to rain, road was wet. Went all the way home no issues. Until the next time, I took it out and similar set up.
Fluid is up, but now not pretty pink. Darker.
It has a new radiator specifically for that truck.
Engine coolant is running around 180 degrees,
I do not know the trans temp.

Do I need a separate trans cooler and better fans. ( It has the stock fan)
Will the gearing that I mention earlier be a partial culpret. The effective gearing it has now, if I did the formula correctly, is approximately 3:38. Due to the 34" tire size,

Any help is greatly appreciated.
Thanks again.
Rick T.
 

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The 246 has a module under the dash that controls TC function.
The factory manuals have a section for diagnosis of the system, with some diagnostic tool only a dealer probably has.

I have always removed the electric shift TCs and put in the old reliable 241C, manual level on the floor and deleted a rats nest of unneeded wiring in the dash and engine harness.

Simpler is better.

Sorry I can't offer more.
 

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Discussion Starter · #6 ·
Thank you Juanni: Funny thing is I purchased a Junk yard 241 manual and was going to do that. But somehow I got talked out of it before buying a new one. Should Listened to my gut.
RIck
 

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You are welcome.
To elaborate further the only communication between the TC and the Auto Trans or ECM is the TC letting the ECM know the TC is in low range. This is accomplished by a gray/black striped wire from the ECM to the TC (usually circuit 1694). When in low range a switch is closed and that gray/black wire is grounded at the TC.
End result is now the trans will upshift at slow speeds, otherwise it won't.

The TC mounts the VSS, Vehicle Speed Sensor too. Which of course tells the EMC the vehicle speed.
 
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