1998 k1500 5.7 with 4L60E wiring/shift issues

[Tonkaobs]

hey guys ! First post here I have a 1998 gmc sierra 5.7L 4L60E 4speed NP243C electric transfer case 4wd obviously. 50k on trans 140k on motor. It’s lifted 10 inches on 35s I just wanna give a quick motor and mods list before I go down my rabbit hole.


Ok first problem —
last week my straps flew off my u joints and my drive shaft fell out on the highway. So fun considering I just got this driveshaft cut specifically for my truck build and spent 800$.

Second problem


it split the transfer case adapter in half so I pulled out transfer case rebuilt and re sealed transfer case. put a new adapter in obviously.

Third problem -


All was well besides the fact I way over filled the trans by 3-4 quarts realized this very soon only drove 5 miles like this.

FIX for third problem -


I drop the Trans pan to let fluid out and changed the gasket and filter while I was in there. Yes I put the new seal in for the filter and I dropped the pan twice to make sure the filter was sealing and not sucking air.

Issue four after “fixing” third problem—


After I dropped the pan the first time and bolted her up she would shift from first to fourth but fourth was very soft feeling? After the truck warmed up it would get stuck in a limp mode and not go out of second. Shortly after a few KOEO cycles and me checking harnesses etc. I got a P1810 TFP valve position switch circuit code. I unplugged the battery and reset the codes truck drove fine for about 8 minutes but every time now that my truck gets up to temps it will go in limp mode.

Other odd ends and outs—

I’m at a loss I ordered the new fluid pressure sensor for it. the truck ran great before the drive shaft incident. Very upset as I just overhauled the is trans and put a shift kit in it 8 months ago. Any help would be amazing. One more this I have CEL on for maf and cam sensor I have replaced those twice the truck runs fine no stalling weird idles etc but no matter how much clearing I do the CEL will not go away for those two codes but it’s been that way for years I don’t think that associates. And a ABS code for a broken left front wheel speed sensor. Again been that way forever I’m not sure they correlate. Please help. thanks for reading !

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[NickTransmissions]

hey guys ! First post here I have a 1998 gmc sierra 5.7L 4L60E 4speed NP243C electric transfer case 4wd obviously. 50k on trans 140k on motor. It’s lifted 10 inches on 35s I just wanna give a quick motor and mods list before I go down my rabbit hole. Ok first problem last week my straps flew off my u joints and my drive shaft fell out on the highway. So fun considering I just got this driveshaft cut specifically for my truck build and spent 800$. it split the transfer case adapter in half so I pulled out transfer case rebuilt and re sealed transfer case. put a new adapter in obviously. All was well besides the fact I way over filled the trans by 3-4 quarts realized this very soon only drove 5 miles like this. I drop the Trans pan to let fluid out and changed the gasket and filter while I was in there. Yes I put the new seal in for the filter and I dropped the pan twice to make sure the filter was sealing and not sucking air. After I dropped the pan the first time and bolted her up she would shift from first to fourth but fourth was very mushy feeling. After the truck warmed up it would get stuck in a limp mode and not go out of second. Shortly after a few KOEO cycles and me checking harnesses etc. I got a P1810 TFP valve position switch circuit code. I unplugged the battery and reset the codes truck drove fine for about 8 minutes but every time now that my truck gets up to temps it will go in limp mode. I’m at a loss I ordered the new fluid sensor for it. the truck ran great before the drive shaft incident. Very upset as I just overhauled the is trans and put a shift kit in it 8 months ago. Any help would be amazing. One more this I have CEL on for maf and cam sensor I have replaced those twice the truck runs fine no stalling weird idles etc but no matter how much clearing I do the CEL will not go away for those two codes but it’s been that way for years I don’t think that associates. And a ABS code for a broken left front wheel speed sensor. Again been that way forever I’m not sure they correlate. Please help. thanks for reading!

Please break that post up into paragraphs as it's just a wall of text no one is going to want to read.

Bullet out the most important things, like the specific issue/problem and anything you may have already done to resolve it.

Only things ive taken away is that you have a lifted truck with a 4L60E in it.

 

[Tonkaobs]

Please break that post up into paragraphs as it's just a wall of text no one is going to want to read.

Bullet out the most important things, like the specific issue/problem and anything you may have already done to resolve it.

Only things ive taken away is that you have a lifted truck with a 4L60E in it.

Is this any better ? sorry lol just in a very frantic mindset right now. this is my daily because my bike is in the shop.

 

[NickTransmissions]

Is this any better ? sorry lol just in a very frantic mindset right now. this is my daily because my bike is in the shop.

What's your final drive ratio? If it's anything less than 4.56 then I'd not spend any time or money on anything else until you restore the factory equivalent ratio so you don't constantly burn up your 3-4 clutch pack.

When you rebuilt the unit 8 months ago, did you:
- Replace all the electronics/electrical components with either AC Delco (shift solenoids A & B + pressure switch manifold assembly), BW (EPC) or Rostra components (harness, 3-2 solenoid, PWM solenoid)?
- Put a Transgo or Sonnax boost valve/sleeve kit in
- Upgrade the 3-4 clutch pack to a 7-9 clutch stack up, .025-.030 or so, load release springs reinstalled?
- Re-machine the pump to restore the working surfaces and rotor/guide clearance to new?

Your other DTCs for the Cam Sensor and MAF have to be addressed as the PCM uses MAF data to regulate line pressure inside the transmission......DO NOT order aftermarket sensors, OEM only! If the MAF is reporting inaccurate air charge numbers, the PCM will give incorrect line pressure management information to the electronic pressure control solenoid, potentially burning up the transmission (meaning you get to overhaul it again).

Your new pressure switch manifold assembly, assuming it's an AC Delco part, should resolve P1810 (caveat: there's no other electrical problems directly or indirectly affecting the transmission).

Hopefully you didn't harm the pump during the very brief time you ran the unit with 5 quarts too much; excessive overfill leads to pump cavitation which destroys the pump via fluid starvation.

 

[Tonkaobs]

What's your final drive ratio? If it's anything less than 4.56 then I'd not spend any time or money on anything else until you restore the factory equivalent ratio so you don't constantly burn up your 3-4 clutch pack.

When you rebuilt the unit 8 months ago, did you:
- Replace all the electronics/electrical components with either AC Delco (shift solenoids A & B + pressure switch manifold assembly), BW (EPC) or Rostra components (harness, 3-2 solenoid, PWM solenoid)?
- Put a Transgo or Sonnax boost valve/sleeve kit in
- Upgrade the 3-4 clutch pack to a 7-9 clutch stack up, .025-.030 or so, load release springs reinstalled?
- Re-machine the pump to restore the working surfaces and rotor/guide clearance to new?

Your other DTCs for the Cam Sensor and MAF have to be addressed as the PCM uses MAF data to regulate line pressure inside the transmission......DO NOT order aftermarket sensors, OEM only! If the MAF is reporting inaccurate air charge numbers, the PCM will give incorrect line pressure management information to the electronic pressure control solenoid, potentially burning up the transmission (meaning you get to overhaul it again).

Your new pressure switch manifold assembly, assuming it's an AC Delco part, should resolve P1810 (caveat: there's no other electrical problems directly or indirectly affecting the transmission).

Hopefully you didn't harm the pump during the very brief time you ran the unit with 5 quarts too much; excessive overfill leads to pump cavitation which destroys the pump via fluid starvation.

I’m not all familiar with the innards of transmissions. I’m a 2nd year ford apprentice still learning everything and this truck has taught me a lot.

I had my uncle who owns a trans shop do the overhaul for me I’m assuming he changed what it “needed” but I can tell you for a fact the solenoids are still factory. I also did indeed order a AC DELCO sensor.

I’m just worried about when I drove it over filled and ruined the pump, valve body etc.

I had a “cateye” before this truck and blew the trans on it at 356k 3-4 went out which is a weak point for the 4L60s. If all else fails I’m going to look into a 4L80 swap.

The part comes in tommore. I can add pictures of the fluid that came out of the trans doesn’t smell burnt either. And I also use only Valvoline max life specific to the vehicle. I can also take pictures of the bottom on the valve body if that means anything.

I have another question aswell. On the passenger side of the transmission there is this big circle harness that plugs directly into the transmission it seems to be wet like it’s seeping fluid it also wiggles around excessively. It’s a big circle harness with a hella lot of wires any idea what that is ?

Also how hard is it to change the shift solenoids.

thanks, Kirk.

 

[Tonkaobs]

I’m not all familiar with the innards of transmissions. I’m a 2nd year ford apprentice still learning everything and this truck has taught me a lot.

I had my uncle who owns a trans shop do the overhaul for me I’m assuming he changed what it “needed” but I can tell you for a fact the solenoids are still factory. I also did indeed order a AC DELCO sensor.

I’m just worried about when I drove it over filled and ruined the pump, valve body etc.

I had a “cateye” before this truck and blew the trans on it at 356k 3-4 went out which is a weak point for the 4L60s. If all else fails I’m going to look into a 4L80 swap.

The part comes in tommore. I can add pictures of the fluid that came out of the trans doesn’t smell burnt either. And I also use only Valvoline max life specific to the vehicle. I can also take pictures of the bottom on the valve body if that means anything.

I have another question aswell. On the passenger side of the transmission there is this big circle harness that plugs directly into the transmission it seems to be wet like it’s seeping fluid it also wiggles around excessively. It’s a big circle harness with a hella lot of wires any idea what that is ?

Also how hard is it to change the shift solenoids.

thanks, Kirk.

If I replaced the MAF with a OEM one it’s currently duralast I used to work at AUTOZONE so I got parts cheap if that doesn’t fix the code could it be the CAI instead of factory intake ?

Thanks, Kirk.

 

[NickTransmissions]

I’m not all familiar with the innards of transmissions. I’m a 2nd year ford apprentice still learning everything and this truck has taught me a lot.

I had my uncle who owns a trans shop do the overhaul for me I’m assuming he changed what it “needed” but I can tell you for a fact the solenoids are still factory. I also did indeed order a AC DELCO sensor.

I’m just worried about when I drove it over filled and ruined the pump, valve body etc.

I had a “cateye” before this truck and blew the trans on it at 356k 3-4 went out which is a weak point for the 4L60s. If all else fails I’m going to look into a 4L80 swap.

The part comes in tommore. I can add pictures of the fluid that came out of the trans doesn’t smell burnt either. And I also use only Valvoline max life specific to the vehicle. I can also take pictures of the bottom on the valve body if that means anything.

I have another question aswell. On the passenger side of the transmission there is this big circle harness that plugs directly into the transmission it seems to be wet like it’s seeping fluid it also wiggles around excessively. It’s a big circle harness with a hella lot of wires any idea what that is ?

Also how hard is it to change the shift solenoids.

thanks, Kirk.

Ok, thought you had done the overhaul...Yea, have to assume he did everything that should have been done given the aplication.

So what's your final drive ratio?

Answer the and I'll respond to your other questions...

 

[Tonkaobs]

Ok, thought you had done the overhaul...Yea, have to assume he did everything that should have been done given the aplication.

So what's your final drive ratio?

Answer the and I'll respond to your other questions...

I just asked him, pretty sure it’s 4.7 ? He can’t really remember sorry I’m not helping a whole lot here but I’m just going off what he says.

 

[NickTransmissions]

I just asked him, pretty sure it’s 4.7 ? He can’t really remember sorry I’m not helping a whole lot here but I’m just going off what he says.

Is this your truck or someone else's? Getting confused as to why you'd need to ask someone the details about your own vehicle.

Anyways, changing shift solenoids and the pressure switch manifold assy are easy but you are focusing on paper cuts while it sounds like the patient (truck) is having/just had a heart attack...Here's the things you need to nail down:

1. Why did the yoke straps fail? Did you replace the pinion yoke with a new one and new hardware in addition to new U joints for your drive shaft so this doesn't happen again?
2. You need to confirm your final drive ratio for the reasons I stated above
3. Autozone MAFs wont cut it (or any electric/electronic part from Autozone, OReilly's or any of those common auto parts stores

Order a Rostra transmission harness for 1993-2002 (you'll need to google the part number, I dont have them memorized) - that 'big circle harness' is your vehicle to transmission case connector that plugs into the harness connector...Sounds like either the o-ring is leaking or the one or more of the locking tabs are broken...I'm guessing none of your electronics were replaced, if this is happening so soon after the 'rebuild'. No transmission that takes electrical or electronic parts leaves my shop without all those old parts thrown in the trash and new OEM or Rostra/Borg Warner/Delphi replacements installed.

Did you have the 35 inch tires before the transmission was rebuilt?

 

[Tonkaobs]

Is this your truck or someone else's? Getting confused as to why you'd need to ask someone the details about your own vehicle.

Anyways, changing shift solenoids and the pressure switch manifold assy are easy but you are focusing on paper cuts while it sounds like the patient (truck) is having/just had a heart attack...Here's the things you need to nail down:

1. Why did the yoke straps fail? Did you replace the pinion yoke with a new one and new hardware in addition to new U joints for your drive shaft so this doesn't happen again?
2. You need to confirm your final drive ratio for the reasons I stated above
3. Autozone MAFs wont cut it (or any electric/electronic part from Autozone, OReilly's or any of those common auto parts stores

Order a Rostra transmission harness for 1993-2002 (you'll need to google the part number, I dont have them memorized) - that 'big circle harness' is your vehicle to transmission case connector that plugs into the harness connector...Sounds like either the o-ring is leaking or the one or more of the locking tabs are broken...I'm guessing none of your electronics were replaced, if this is happening so soon after the 'rebuild'. No transmission that takes electrical or electronic parts leaves my shop without all those old parts thrown in the trash and new OEM or Rostra/Borg Warner/Delphi replacements installed.

Did you have the 35 inch tires before the transmission was rebuilt?

Yes this is my truck I’ve done everything to it besides the trans rebuild so I don’t know much about it I just know I told him I wanted a shift kit and overhaul and a couple weeks later it was done. When I first got the truck it had a bad 3-4 clutch pack.

1. Yes I replaced the yoke new unjoints all around new hardware and straps I used some doorman straps that obviously couldn’t take it so I got some through the dealer this time around and changed yoke and unjoints again because falling out and claiming around isn’t very good for the drive shaft or joints.

2. I’m not very sure I’ll be able to confined the final drive ratio he told me 4.7 just earlier but I don’t think that sounds correct IMO.

3. The wires on the harness look fine coming out of the transmission wondering if there is anyway to replace the connecter side of said harness that’s actually inside of the transmission. All clips on the outside of the harness are fine and not broken.

4. I’m still just so confused how this all happened so suddenly and how the truck will drive fine for about 10 minutes then will register the P1810 code and won’t go past second gear. P R N D all seem to work and go into gear amazing when truck is cold. Fluid is right on the top cold mark to a T. Again yes this is my truck and it’s been my baby and project with my fiance for a couple years now.

Extra- plan on getting a new daily car when I get out of basic I ship in two weeks and just overhauling the truck completely but as of now I just want to get her back on the road to enjoy her she’s old high miles she’s going to complete kick the bucket eventually. Last owners before me did not maintain the truck at all. I found this out through putting in the used motor with a friend putting in the lift kit with new front and rear end. Just everything I’ve done to the truck every time I fix something a week later something else breaks at what point do I just sell it or do a full frame off build. With 6k in the hole I’ve spent fixing it I’d of probably been better off just doing a frame off ATP.

Thanks again, Kirk.