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Discussion Starter · #1 ·
Got a question:

2001 K1500 4x4 5.3L Suburban 4L60-E
286,000 miles, but runs like a top. If it needs attention, it gets it right now.

Before we left out Friday, I had all of the fluids changed out, synthetic in every thing. ( not the Anti-freeze )

The truck used to belong to a Amsoil dealer…. So I continued using Synthetics, just not Amsoil, grossly over-priced...

8,000 lb Toy Hauler, went across the CAT scales yesterday, and the truck/trailer weighs 16,140 lbs. Includes my 420 lb Piaggio 250cc scooter.

Obviously, the truck is under powered for what I am doing, but my retirement pension and savings can only go so far, before the rubber band breaks.

What I want to do, is learn where to tap into the control lines to the transmission so that anytime, it is NOT in 3rd gear, that a Relay will be operated that will open the 12V lead to the A/C compressor clutch. Then when the tranny shifts back to 3rd the A/C resumes again.

The truck performs sufficiently well for me, IF, I turn the AC OFF when climbing hills.

I’m 80 y/o and in no hurry, when I get there is soon enough….

But, the engine is much happier without the A/C when climbing hills …

I will put a switch on the relay line to defeat this when no trailer is involved, e.g., need the tranny to work like the factory made it.

( I sure do miss my ‘98 Dodge diesel dually – sniff, dumb dumb to let it go :( )

just as a side note, drove from Tulsa, OK to Ogallala, NE and the engine temp stayed at 195*F in 99*F temps all the way...
( I have added a good Transmission Cooler with a big ass fan sucking air thru it )

I have all of the Schematics for the truck.
 

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Discussion Starter · #4 ·
I'd use the shift relays.
And the AC clutch relay.
And you want AC in Park and Neutral.
Many thanks for this:

Park & Neutral I can handle with a Toggle switch to prevent my mods from being effective. The only time I want this mod to be used, is after I get on the highway & pulling the Toy Hauler.

I had not investigated the AC clutch circuit, so thanks for that tip.
This trip is going to stay with my fingers turning off the AC manually....
after we get back home July 1, then I will start working on this mod.

My sister lives in Price, UT and there are a lot of "steep hills" to climb between Tulsa, OK and Price, UT.

I have worked in the Borger, TX area for 11 years, then in the Roswell-ABQ-Farmington, NM area for 15 years....
Then Grouse Creek, UT up in the NW corner of UT for a year.....
( loved that job, flew the company airplane all over UT & Nevada )

So very familiar with all of I-40 in its' Disrepair status, and hills..... super long hills east of Moriarty to Tucumcari.

Anyway, around Sept-Oct we are going to see my sister in Price, UT...
it would be super nice for this Mod to be working by then.

Wish I had the 3/4 ton Suburban with the diesel engine..... maybe I don't with Diesel now over $6 in some places :( :eek:


On this trip alone, from Salina, KS to Ogallala, NE section of roads, the hills are undulating up, down, up, down, up down..... a super PITA to keep having to turn the AC off.

Not going to turn off the Fans, AC is always in Recirculate Mode, just want the AC Clutch to deactivate when I push on the Throttle to downshift to 2nd gear, then when the Cruise shifts back to 3rd gear, AC compressor works again.

I never allowed OD to be used while towing.

If I can find a 2000-2004 Ford Excursion with the V10 for a decent price, will buy that for the towing trips....

This is how this last portion of my trip has done on MPG....
you can sure see how the flat lands of OkieLand disappeared and the Hills of KS and NE appeared. This is the Fuelio App in Android, it is in reverse order of course, as each new fill-up appears at the top of the screen.


Communication Device Font Gadget Screenshot Electronic device
 

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Discussion Starter · #5 ·
Reviewing the Shift Pattern chart,
I note that I will need two Relays in series to accommodate 3rd gear only turning OFF the AC Clutch. Going to have to use DPDT relays, it seems.

no problem, my avocation has been Electronics since 1958 and Digital control circuits are easy for me.

didn't add that I worked for Phx Fire Dept in the 911 Tech Mntc department, our group installed, maintained all of the Dispatching Computers for 257 fire stations, every single one in Maricopa County, AZ.... 20 years there, loved AridZona but a Semi hit me in 2008 and destroyed my capability to deal with temps over 85*F so I moved back to OkieLand where I was raised. don't like the Humidity here though :censored:
 

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2001 Suburban 5.3L, 302.2k miles
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@AZgl1800 , when towing, have you tried turning on the Tow/haul switch? It changes the shift points and prevents the transmission from going to overdrive when towing. It helps a lot keeping the rpm in the torque range for towing.
However it will not turn off the HVAC unless its at WOT.
Don't tow in D as the 3/4 clutch will wear out quickly.

Just read that you don't use overdrive.
" I never allowed OD to be used while towing."
 

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More question than answer, but, assuming your '01 is substantially similar to my '98, all of those things (AC and transmission and such) are controlled through the main computer. I wonder if one of those programmers would be able to simply add the desired logic to the main computer (if tow/haul mode is active and speed is above 15 mph and transmission is in 1 or 2 then turn off AC compressor).
 

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AZ, I was originally thinking 2 relays as well. But looking at the shift solenoid pattern, the B solenoid is off in 3rd and in 4th gear, and operated in 1st and 2nd.
This allows you to parallel a relay that operates in 1st and 2nd gears and would release in 3rd.
Just insert the normally closed contacts, of the new relay, in the AC clutch relay operate path.

I'd use something like this:

Light Product Rainbow Font Material property
 

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Discussion Starter · #9 · (Edited)
Ray,
I think we are on the same page.
DPST Normally Close - relays set so that in the relaxed position, the AC clutch would work normally as designed.

oops!
went back and reread your post, you are correct, only need 1 relay. I can use 2 steering diodes to operate the one relay.

We climbed a lot hills today, the truck did fine, as long as, the AC was off.
Except for one occasion going through Wind Cave National Park, US-385, some idiot decided that my 45 mph was too damn slow for him ( 65 zone ) and passed me on a right hand curve!!! )

Had I not hit the brakes and pulled to the edge of the Berm, he would have hit a camper full of kids head on. :mad::eek:

I have a FalconEye Rear View camera over the top of the Toy Hauler's ramp door.
I saw him start to pull out and then he was in my left side mirror, and I could see the big camper coming around another Right Hand turn, they would have met in the middle of the two tight turns.... that big 7 inch Screen saved some lives today.
 

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Got a question:

2001 K1500 4x4 5.3L Suburban 4L60-E
286,000 miles, but runs like a top. If it needs attention, it gets it right now.

Before we left out Friday, I had all of the fluids changed out, synthetic in every thing. ( not the Anti-freeze )

The truck used to belong to a Amsoil dealer…. So I continued using Synthetics, just not Amsoil, grossly over-priced...

8,000 lb Toy Hauler, went across the CAT scales yesterday, and the truck/trailer weighs 16,140 lbs. Includes my 420 lb Piaggio 250cc scooter.

Obviously, the truck is under powered for what I am doing, but my retirement pension and savings can only go so far, before the rubber band breaks.

What I want to do, is learn where to tap into the control lines to the transmission so that anytime, it is NOT in 3rd gear, that a Relay will be operated that will open the 12V lead to the A/C compressor clutch. Then when the tranny shifts back to 3rd the A/C resumes again.

The truck performs sufficiently well for me, IF, I turn the AC OFF when climbing hills.

I’m 80 y/o and in no hurry, when I get there is soon enough….

But, the engine is much happier without the A/C when climbing hills …

I will put a switch on the relay line to defeat this when no trailer is involved, e.g., need the tranny to work like the factory made it.

( I sure do miss my ‘98 Dodge diesel dually – sniff, dumb dumb to let it go :( )

just as a side note, drove from Tulsa, OK to Ogallala, NE and the engine temp stayed at 195*F in 99*F temps all the way...
( I have added a good Transmission Cooler with a big ass fan sucking air thru it )

I have all of the Schematics for the truck.

I have a 1994 Chevrolet Suburban Silverado, 5.7 V8 with the 4L60E transmission. I have pulled 8,000 lbs. behind me with no issues and the AC was running the whole time. I too put my Suburban and 20 foot flatbed hauling a 1951 Dodge Powerwagon military truck on the CAT scales, 14,200 lbs! I know, that is a lot BUT....I neatly installed an RV transmission cooler in the front behind the grille to give me 3 transmission coolers including a temp gauge for the transmission, the sender is in the pan. The trans temp never got over 160 degrees and YES...IT IS HOT here in Florida. I NEVER towed anything in overdrive on the 4L60E transmission. I had the transmission swapped out at 251,000 miles in 2013 and I JUST now got around to rebuilding the original GM transmission that came with the truck and guess what? The inside was spotless, NO burned clutch frictions OR steels, I was SHOCKED! I did perform my own homemade flushing with my homemade system for the transmission at about every 50,000 miles and it paid off. I would never flush a transmission that has NEVER been done and has 100,000 miles on it yet SOME shops push it, NOT GOOD!! Flushing is ok if you start off doing it on a regular basis like I did. You mentioned you are not in a hurry and that IS THE KEY, you can pull weight but you HAVE to compensate for it BEFORE you approach a hill, some drivers just floor the gas pedal when going uphill........not good. Anyhow, hope this helps. Remember, heat is the number one destroyer of transmissions. I will try to post a picture of a trans temp chart that will give you some idea of how heat really affects a transmission. Good luck!
 

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Discussion Starter · #11 ·
I have a 1994 Chevrolet Suburban Silverado, 5.7 V8 with the 4L60E transmission. I have pulled 8,000 lbs. behind me with no issues and the AC was running the whole time. I too put my Suburban and 20 foot flatbed hauling a 1951 Dodge Powerwagon military truck on the CAT scales, 14,200 lbs! I know, that is a lot BUT....I neatly installed an RV transmission cooler in the front behind the grille to give me 3 transmission coolers including a temp gauge for the transmission, the sender is in the pan. The trans temp never got over 160 degrees and YES...IT IS HOT here in Florida. I NEVER towed anything in overdrive on the 4L60E transmission. I had the transmission swapped out at 251,000 miles in 2013 and I JUST now got around to rebuilding the original GM transmission that came with the truck and guess what? The inside was spotless, NO burned clutch frictions OR steels, I was SHOCKED! I did perform my own homemade flushing with my homemade system for the transmission at about every 50,000 miles and it paid off. I would never flush a transmission that has NEVER been done and has 100,000 miles on it yet SOME shops push it, NOT GOOD!! Flushing is ok if you start off doing it on a regular basis like I did. You mentioned you are not in a hurry and that IS THE KEY, you can pull weight but you HAVE to compensate for it BEFORE you approach a hill, some drivers just floor the gas pedal when going uphill........not good. Anyhow, hope this helps. Remember, heat is the number one destroyer of transmissions. I will try to post a picture of a trans temp chart that will give you some idea of how heat really affects a transmission. Good luck!
you and I are on the Same Page.
When approaching the bottom of a hill, I already have it in 2nd gear, and taching about 4500 and hold it there, I don't push it harder than that.

Turning off the a/c gives a very noticeable HP increase going up the grades, it will gain speed w/o the a/c, while it just maintains speed with the a/c ON.

I bought the truck at 212,000 miles from a guy who was an Amsoil dealer. He told me that he ran full synthetics in every thing... I have no way to disprove that, but I favor Synthetics anyway, so continued doing that. the truck now is showing 283k+ miles on the Odometer.

I had the Transmission filter changed 3 weeks ago, and the recommended Dexron III was put in, it came from O'Reilly's and is their brand.

I took a picture of the magnet in the pan because I wanted to see what it looked like. That is the only "proof" I have of previous maintenance.


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