2002 LM7/4L65E Swap limp mode

[Ole Greenie]

Hi everyone,

I've been deployed so it has been a while. I am in need of some assistance concerning a recent 4l65E install that replaced my BTO 700R4...particularly concerning a limp mode condition.

So I have looked up a few previous threads but it is still a bit unclear as to what a solution might be.

Conditions:
1) Motor runs perfectly. 2002 LM7 with 4l60E (not in truck). Cable throttle.
2) Place selector into R and it wants to die. After engine warms up, all is well.
3) Place in D, it starts in 3rd gear...limp mode.
4) I can manually shift into lower gear and all is fine but it does not go into 1st gear. It starts in 2nd gear. Is this normal?
5) No engine codes. Bosch scanner does not read trans codes (maybe I should get one!)
6) Transmission (4l65E) is not "married" to the PCM. Meaning that the trans is foreign to the PCM. PCM and engine came together.
7) Painless harness 60217.
8) Everything is connected perfectly.
9) On hold with Painless for 45 minutes...hung up. What a pain!

I'm inclined to think that I need another PCM reflash. I have no idea what was programmed before...but it ran fine with the 700R4. Thoughts?

Much appreciation in advance!
John

[BR3W CITY]

Trans needs computer correctly identified and things like tire size etc updated for practical things like speedo output. If the trans and computer dont' mesh, itll lock you in 3rd to get you home.

Your scanner should show P, T and U Codes to be useful.

[Clyde65]

I believe non computer controlled trans' are programmed as manuals so the pcm doesn't expect anything from it.

[Ole Greenie]

Okay, Still having a hard time deciphering all the conflicting information. I've been told I don't have to reprogram the PCM and also that it needs to be reprogrammed. I've also been told that the pinouts are different between a 4L60E and a 4L65E (which I highly doubt). Could someone confirm this? (PCM was programmed for a 4L60E)

Texas speed says that it should work without reprogramming. What gives and what should I do?

Should I buy a code scanner and a programmer? Big bucks!!

Thanks...John

[BR3W CITY]

When you had the original setup done, was the computer programmed knowing you'd be running the 700r4? If so, then they probably setup the ECM like a manual, which is what I think Clyde was getting at. In that circumstance, you need the computer reflashed for the automatic trans you'll be using (4l60/65/70 or 4l80e). This is how it knows which config to use for things like ISS/VSS input, NSS, range selector input. etc.

4l65e hooks up just like the 60e, just has 5 planetaries in the case.

[LeesTruk]

John, your problem sounds exactly what I faced when I did my swap. Turned out to be a faulty PCM. Could've been a bad reflash. A company was referred to me (PCMperformance,com) that dealt with reprogrammimg/selling PCM,s. They had me fill out a worksheet as to what I had/wanted, then I purchased a new PCM from them. It was like someone turned on a switch, and the truck woke up and ran beautifully! It's amazing that you can have both performance AND fuel efficiency. As for your transmission, it indeed, needs to be connected to the PCM for proper function.

Lee

[Ole Greenie]

Originally Posted by LeesTruk

John, your problem sounds exactly what I faced when I did my swap. Turned out to be a faulty PCM. Could've been a bad reflash. A company was referred to me (PCMperformance,com) that dealt with reprogrammimg/selling PCM,s. They had me fill out a worksheet as to what I had/wanted, then I purchased a new PCM from them. It was like someone turned on a switch, and the truck woke up and ran beautifully! It's amazing that you can have both performance AND fuel efficiency. As for your transmission, it indeed, needs to be connected to the PCM for proper function.

Lee

Hey Lee and everyone who chimed in...

So, I took it to a tuning shop. I must me climbing the "AGE" ladder or something but they told me that the trans program within the PCM had been turned off. Then it all rang a bell! Since I had originally mated the 5.3 to a 700R4, I had requested to make the program like a manual transmission...3 years ago.

Anyway, 2 days and $300 later, I am on the road. I feel kind of stupid but thankfully it was something realitively simple to remedy. Everything works as it should, but definitely will have to take it back to adjust.

I'll tell you what (southern emphasis), this is prolly the best thing I could have done...LS and built (Mad Dog Transmissions, Cumming, GA) 4l65e swap. This thing runs like a scalded dog. The down shift from 2nd to 1st is simply exhilerating! Just burns the tires...275s with Eaton LSD out back. This combo works well together as I never imagined a $900 LM7 5.3 (w/80K) would ever be able to beat a hemi charger today (street racing is illegal! ). No cats, cam, and headers certainly help. Mustangs may be a bit different...as that Coyote is a really good motor.

So, Lee and the others, I'm having a ton of fun! Thanks so very much for your candid mentorship and accumen. This thing is a beauty to drive (purists are pretty special too!) but if more knew just how well these drive coupled with the imense power (given 3500 lbs.)...more would be doing this swap. Looking back, it is definitely worth the time and expense. Now I have to fly to AZ to help my dad with his 67 3/4 ton 2006 LQ4/LS2 cam and 4L80e swap!

Very best to all...John

[Ole Greenie]

Originally Posted by BR3W CITY

When you had the original setup done, was the computer programmed knowing you'd be running the 700r4? If so, then they probably setup the ECM like a manual, which is what I think Clyde was getting at. In that circumstance, you need the computer reflashed for the automatic trans you'll be using (4l60/65/70 or 4l80e). This is how it knows which config to use for things like ISS/VSS input, NSS, range selector input. etc.

4l65e hooks up just like the 60e, just has 5 planetaries in the case.

This was exactly the case! Trans was turned off in the PCM! Thanks brother!