1998 k1500 5.7 with 4L60E wiring/shift issues

[NickTransmissions]

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.

There were no 4.7 ratios for those diffs, or any GM truck axle housing/assembly that I'm aware of...for trucks, think there's 3.42, 3.73 (G80 diff), 4.10, 4.56, 4.88, 5.10 (or something similar)...Here's how you can confirm your final drive ratio: Make a paint mark on your rear tire then rotate the marked tire one revolution while counting how many times the driveshaft rotates. eg, If your driveshaft made 3.75 revolutions, that would determine a 3.73 gear ratio.

You can replace the wiring harness with the Rostra 1993-2002 part I mentioned above - that would solve the leak there and also eliminate the possibility that the harness is the true source of your DTCs / Limp mode...again, I'd ask exactly what was done - if you don't know about automatic transmissions, you can learn.

Given you're a Tech apprentice, you'll want to know at least the basics, including servicing, diagnosis as well as some of the more frequently used terminology for relevant parts, procedures and other things related to transmissions. You may not be rebuilding them but you will likely be working on them to some extent as a Ford tech (I rebuild GM, Ford and Dodge transmissions so am familiar with all three OEMs when it comes to auto transmissions).

So here's what I'd do at this point...

1. Confirm your final drive ratio following my instructions above
2. Replace your harness and pressure switch manifold assembly; continuity test all other solenoids with a DVOM
3. Go over the underside of your truck and engine bay with a fine tooth comb looking for loose / missing / damaged wiring, grounds, etc
4. Use a bidirectional scan tool on your first test drive after the repairs - monitor the engine and transmission data to make sure the transmission is being properly commanded/controlled by the PCM (if not, that may be the problem)
5. Find out exactly what was done when the transmission was rebuilt. Refer to my 4L60E information thread for guidance and let me know if you want help framing your questions

IF that shop knew you had a lifted truck and didnt ask you about your final drive (assuming you have at least a 4.10 ratio and they already knew that) then I'd never have that shop make me a cup of coffee much less rebuild me a transmission.

Any time a prospect calls me up asking for rebuild quotes and tells me he owns a truck or SUV, first thing I ask beyond the vehicle year, make, model, symptoms is, "Is your truck lifted with big tires?".

If the answer is "Yes", the very next thing out of my mouth is "Did you upgrade the final drive and if so, to what ratio?".

If the answer is "No", I decline the job and educate the customer as to why and to put a deeper ring and pinion set(s) before blowing money on the transmission.

 

[Tonkaobs]

There were no 4.7 ratios for those diffs, or any GM truck axle housing/assembly that I'm aware of...for trucks, think there's 3.42, 3.73 (G80 diff), 4.10, 4.56, 4.88, 5.10 (or something similar)...Here's how you can confirm your final drive ratio: Make a paint mark on your rear tire then rotate the marked tire one revolution while counting how many times the driveshaft rotates. eg, If your driveshaft made 3.75 revolutions, that would determine a 3.73 gear ratio.

You can replace the wiring harness with the Rostra 1993-2002 part I mentioned above - that would solve the leak there and also eliminate the possibility that the harness is the true source of your DTCs / Limp mode...again, I'd ask exactly what was done - if you don't know about automatic transmissions, you can learn.

Given you're a Tech apprentice, you'll want to know at least the basics, including servicing, diagnosis as well as some of the more frequently used terminology for relevant parts, procedures and other things related to transmissions. You may not be rebuilding them but you will likely be working on them to some extent as a Ford tech (I rebuild GM, Ford and Dodge transmissions so am familiar with all three OEMs when it comes to auto transmissions).

So here's what I'd do at this point...

1. Confirm your final drive ratio following my instructions above
2. Replace your harness and pressure switch manifold assembly; continuity test all other solenoids with a DVOM
3. Go over the underside of your truck and engine bay with a fine tooth comb looking for loose / missing / damaged wiring, grounds, etc
4. Use a bidirectional scan tool on your first test drive after the repairs - monitor the engine and transmission data to make sure the transmission is being properly commanded/controlled by the PCM (if not, that may be the problem)
5. Find out exactly what was done when the transmission was rebuilt. Refer to my 4L60E information thread for guidance and let me know if you want help framing your questions

IF that shop knew you had a lifted truck and didnt ask you about your final drive (assuming you have at least a 4.10 ratio and they already knew that) then I'd never have that shop make me a cup of coffee much less rebuild me a transmission.

Any time a prospect calls me up asking for rebuild quotes and tells me he owns a truck or SUV, first thing I ask beyond the vehicle year, make, model, symptoms is, "Is your truck lifted with big tires?".

If the answer is "Yes", the very next thing out of my mouth is "Did you upgrade the final drive and if so, to what ratio?".

If the answer is "No", I decline the job and educate the customer as to why and to put a deeper ring and pinion set(s) before blowing money on the transmission.

SORRY I thought you were asking about the 1-2-3-4 trans gear ratios the diff is 4.10 ratio I know that for 100% certainty because I did that myself a couple weeks before I actually put it in the shop for the over haul.

I isnepcted the harnesses under the truck today and everything seems fine. When the truck leaked fluid everywhere from splitting the transfer case adapter some of the harnesses got soaked in ATF should I clean though with parts cleaner aswell just to be sure that isn’t the issue?

Also if this helps I replaced all engine and body grounds about 3-4 weeks ago because the truck sat for awhile (lost motivation). Also replaced the entire steering column assembly with all OEM parts. Mine was pretty trashed from previous owners.

Do you know how I can test / check the shift solenoids and what good and bad specs for them are ? Also I don’t have any fancy scanners should I take it to a shop for that after I try my fixes too see if anything else is wrong or what’s happening inside the PCM and what it’s commanding and what’s not happening ya know ?

How “hard” is it to just do a 4L80 swap obviously I have to get new harnesses etc correct ? Will it bolt directly to the 5.7 or do I need and adapter plate for that ?

Thanks, Kirk.

 

[NickTransmissions]

SORRY I thought you were asking about the 1-2-3-4 trans gear ratios the diff is 4.10 ratio I know that for 100% certainty because I did that myself a couple weeks before I actually put it in the shop for the over haul.

I isnepcted the harnesses under the truck today and everything seems fine. When the truck leaked fluid everywhere from splitting the transfer case adapter some of the harnesses got soaked in ATF should I clean though with parts cleaner aswell just to be sure that isn’t the issue?

Also if this helps I replaced all engine and body grounds about 3-4 weeks ago because the truck sat for awhile (lost motivation). Also replaced the entire steering column assembly with all OEM parts. Mine was pretty trashed from previous owners.

Do you know how I can test / check the shift solenoids and what good and bad specs for them are ? Also I don’t have any fancy scanners should I take it to a shop for that after I try my fixes too see if anything else is wrong or what’s happening inside the PCM and what it’s commanding and what’s not happening ya know ?

How “hard” is it to just do a 4L80 swap obviously I have to get new harnesses etc correct ? Will it bolt directly to the 5.7 or do I need and adapter plate for that ?

Thanks, Kirk.

Ok...So when someone says "final drive" they are referring to the differential...The transmission's gearing is 3.08 (1st), 1.54 (2nd), 1 (3rd) .67 (4th)...multiply each of those gear ratios by the final drive ratio to get your total mechanical leverage figure the powertrain has when in a given forward gear (i forget exactly what reverse gear ratio is, doesn't usually matter).

Check out my 4L80E video on testing solenoids - it's the same process for the 4L60E and will show you exactly what to do. The following resistance values indicate good continuity:

- Shift Solenoids A&B and 3-2 control solenoid: 19-25 ohms

- PWM Solenoid: 9-12 ohms

- EPC: 4-5.5 ohms

 

[Road Trip]

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.

Greetings Tonkaobs,

Welcome to the GMT400 forum! There are a lot of fellow GMT400 enthusiasts in here with
a ton of experience & they are willing to share it. You've already got one of the resident transmission SMEs
giving you some valuable guidance, so do what you can to answer his questions and you will end up way
ahead of the game.

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.

It sounds like your VCM in your '98 is setting the SES (Service Engine Soon) light and
is storing DTCs? (Diagnostic Trouble Codes) I'm not being pedantic, I just want you to
be able to easily find/reference these error codes in the GM Factory Service Manuals.
(More on that in a minute.)

Anyway, we like to help others who are trying to keep yet another GMT400 truck on the
road. But way over here in upstate NY I am only aware of the details that you describe.

In other words, Help Us Help You. Please list any/all DTCs that your computer is kicking.
More specificially, I am interested in your MAF and cam sensor DTCs. Quite possibly we
can help you get those cleared up. And if Nick says that bad MAF readings are detrimental
to your transmission because of erroneous line pressure, then that's a huge tip to help avoid
repeat failures, and you should heed his warning.

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

I am among several members in this forum who are either currently serving in the military or are prior service / veterans.
Good on you for your willingness to volunteer/serve your country. FWIW, this predisposes me to want to help you get
to where you are going.

Speaking of which, here's another inside tip that will get people interested in your issues and join in the fun.
I've observed 2 different styles with folks who are new to this forum. The first style try to use the forum
like it's a vending machine. Push button to get answer, shake machine when it doesn't dispense what they want immediately?
And when we don't have a specific answer for their vaguely defined question, they get upset & disappear?

Nobody wants that to happen. And for you, so far so good. But here's the secret to your success. There
is nothing better to use as a repair guide on your GMT400 than the General's FSMs. (Factory Service Manuals.)
If you prefer books, buy a complete used set at ebay or a used bookstore. (In the attached is the best $50 + shipping
that I've spent on my chore truck to date.)

On the other hand, there is a cache of digital FSMs for the '88+ GMT400s over here that you can download for free: (The Good Stuff)

If you have a laptop, download the books for your year and start drinking deep from the fire hydrant of knowledge.
And after all that setup, this is what I wanted to share. Those members who come in here, state that they are suffering
from a long time P1345 DTC, they've read about it in the FSM, but would like some of the details explained to them...well,
those folks get plenty of assistance right away. Everyone likes to help those who are trying to help themselves.

****

Again, welcome to the forum. And keep in mind that Basic training is pretty much the same thing as all of the above...
it's just concentrated goodness. To be perfectly candid, Basic looked a whole lot better in the Rearview Mirror of Life as
opposed when it was rushing up in the Windshield. :0)

But I'm glad I did it. One of the very best investments I ever made in myself.

Best of luck in your journey. And be sure to let us know how all this turns out.

But first things first. Be sure to share those DTCs with us so that we can start kicking
them around and come up with a reasonable recovery plan.

Safe travels --

 

[Tonkaobs]

Ok...So when someone says "final drive" they are referring to the differential...The transmission's gearing is 3.08 (1st), 1.54 (2nd), 1 (3rd) .67 (4th)...multiply each of those gear ratios by the final drive ratio to get your total mechanical leverage figure the powertrain has when in a given forward gear (i forget exactly what reverse gear ratio is, doesn't usually matter).

Check out my 4L80E video on testing solenoids - it's the same process for the 4L60E and will show you exactly what to do. The following resistance values indicate good continuity:

- Shift Solenoids A&B and 3-2 control solenoid: 19-25 ohms

- PWM Solenoid: 9-12 ohms

- EPC: 4-5.5 ohms

I just wanna say you’re awesome dude thanks !

Greetings Tonkaobs,

Welcome to the GMT400 forum! There are a lot of fellow GMT400 enthusiasts in here with
a ton of experience & they are willing to share it. You've already got one of the resident transmission SMEs
giving you some valuable guidance, so do what you can to answer his questions and you will end up way
ahead of the game.



It sounds like your VCM in your '98 is setting the SES (Service Engine Soon) light and
is storing DTCs? (Diagnostic Trouble Codes) I'm not being pedantic, I just want you to
be able to easily find/reference these error codes in the GM Factory Service Manuals.
(More on that in a minute.)

Anyway, we like to help others who are trying to keep yet another GMT400 truck on the
road. But way over here in upstate NY I am only aware of the details that you describe.

In other words, Help Us Help You. Please list any/all DTCs that your computer is kicking.
More specificially, I am interested in your MAF and cam sensor DTCs. Quite possibly we
can help you get those cleared up. And if Nick says that bad MAF readings are detrimental
to your transmission because of erroneous line pressure, then that's a huge tip to help avoid
repeat failures, and you should heed his warning.



I am among several members in this forum who are either currently serving in the military or are prior service / veterans.
Good on you for your willingness to volunteer/serve your country. FWIW, this predisposes me to want to help you get
to where you are going.

Speaking of which, here's another inside tip that will get people interested in your issues and join in the fun.
I've observed 2 different styles with folks who are new to this forum. The first style try to use the forum
like it's a vending machine. Push button to get answer, shake machine when it doesn't dispense what they want immediately?
And when we don't have a specific answer for their vaguely defined question, they get upset & disappear?

Nobody wants that to happen. And for you, so far so good. But here's the secret to your success. There
is nothing better to use as a repair guide on your GMT400 than the General's FSMs. (Factory Service Manuals.)
If you prefer books, buy a complete used set at ebay or a used bookstore. (In the attached is the best $50 + shipping
that I've spent on my chore truck to date.)

On the other hand, there is a cache of digital FSMs for the '88+ GMT400s over here that you can download for free: (The Good Stuff)

If you have a laptop, download the books for your year and start drinking deep from the fire hydrant of knowledge.
And after all that setup, this is what I wanted to share. Those members who come in here, state that they are suffering
from a long time P1345 DTC, they've read about it in the FSM, but would like some of the details explained to them...well,
those folks get plenty of assistance right away. Everyone likes to help those who are trying to help themselves.

****

Again, welcome to the forum. And keep in mind that Basic training is pretty much the same thing as all of the above...
it's just concentrated goodness. To be perfectly candid, Basic looked a whole lot better in the Rearview Mirror of Life as
opposed when it was rushing up in the Windshield. :0)

But I'm glad I did it. One of the very best investments I ever made in myself.

Best of luck in your journey. And be sure to let us know how all this turns out.

But first things first. Be sure to share those DTCs with us so that we can start kicking
them around and come up with a reasonable recovery plan.

Safe travels --

you guys are awesome ! Currently waiting on my parts to come in this week. I have other big things to focus on like buying my father a headstone. Don’t mean to get personal sorry guys . But I will update you guys if I fix it or just end up yanking out the old 4LE. Also I can’t wait to be apart of the USMC it’s frightening and nerve wracking but I’ll be ok. Again thank all you guys for such help and for your service.

Regards, Kirk.

 

[NickTransmissions]

I just wanna say you’re awesome dude thanks !

you guys are awesome ! Currently waiting on my parts to come in this week. I have other big things to focus on like buying my father a headstone. Don’t mean to get personal sorry guys . But I will update you guys if I fix it or just end up yanking out the old 4LE. Also I can’t wait to be apart of the USMC it’s frightening and nerve wracking but I’ll be ok. Again thank all you guys for such help and for your service.

Regards, Kirk.

You're welcome, Kirk and best of luck to you in the Corps! You'll be fine, especially if you've been focusing on your cardio and anerobic exercises...Condolences for your loss, very sad to hear.

Re the 4L80e, there isnt too much you need to do, just a segement swap for the PCM, drive line cut and rebalance and move your trans x member back. I build 4L80Es for such swaps all the time, may be worth doing for your truck. The 4L80E is the best transmission GM ever installed into a light duty gasoline engine equipped vehicle, IMO.