Transmission code help.

[yukonjon]

So heres the deal. I just put in a mega monster transmission last weekend. Went great and love it. Problem is my torque converter is coming in and out of lockup. It is a new torque converter. I have no check engine light and nothing else noticeable. Called monster and they are telling me to scan the computer for codes. The dealer says if there is no check engine light then there is no code. Monster tells me the code wont necessarily turn on the CEL. I just want a for sure answer on weather a tranny code will pop up without setting of the CEL. Im getting mixed answers from multiple people and was wondering if anyone knew for sure or had personal experience.

I have replaced the throttle position sensor already and looked at the obvious. Next will be speed sensor and brake switch but I want a clear answer on the code or not. Dealer is convinced it would set off a CEL but im not so sure now. This is in a 99 yukon with the 4L60-E tranny. Thanks guys

 

[yukonjon]

Guess this is an uncommon area. Anyone know where I could get a for sure answer?

 

[95TwinTT]

You might want to check with your Tuner about adjustments to the OBDII.

Do you know what year transmission you ended up with? Have you run pressure tests while driving?

If shift points seem to be happening at the proper speed points, it is doubtful that the speed sensor is having a problem.

If I remember right the lock-up was altered through the OBS years somewhat and ended up being controlled by MAF information as well as TPS.

RPM’s also can have an affect on lock-up, as they tend to just have a percentage of lock at lower RPM’s to keep the driving experience smooth.

 

[yukonjon]

Im not sure by what year tranny I have, other than it is the exact same as stock with all upgraded equipment. I havent run pressure test yet but based off my tune and the upgraded tranny my pressure should be higher than normal which wouldnt cause this problem. I plan on hooking one up when i get a chance to make sure there isnt an internal problem with the new transmission. Everything is shifting fine at the correct times and I agree about the sensor. I know a sticky brake switch will cause the problem too but I think mine is good. Im just trying to figure this out without the 95$ an hour shops. The lockup is normal at low speeds and rpms but steady throttle on the interstate is where it is coming in and out of lockup every few seconds. I really need to find out whos right on weather i would get a check engine light with a tranny code. This is becoming very frustrating.

 

[95TwinTT]

At what speed does it first lock up?

What speed does is start slipping out and does it slip out whether it is in 3th or 4rd? If so, is the slipping in and out speed related or RPM related?

 

[SunlitComet]

Type C and D non-emmisions related problems can be stored as active and not turn on the MIL. Get access to a good scanner and report back And I am sure an answer will come quickly.

 

[yukonjon]

Thats exactly what i was wondering about the CEL. Im not sure what the C and D non emissions code refers too but I think i just need to get to a scanner. Its deinetely rpm related. Only does it at steady throttle anywhere between 40 and 80 mph with 1000 to 1800 rpm. Will do it in either 3 or 4th gear. Steady throttle is the main thing. I thionk that there might be a TCC code without a check engine light but ill just have to find a good scanner to pull it up.

 

[SunlitComet]

non-emissions related means anything the does not effect measured gases at tail pipe such as hydrocabons, carbon dioxide, carbon monoxide, oxygen or leaks of fuel vapors. A tranny malfunction will most likely not illuminate the light. Let us know what pops up.

 

[yukonjon]

Guess ill just find a dealer and do it. Ive tested every sensor I could and they all check out. Ill let you know if there is one and no CEL. Thanks for all the help.

 

[95TwinTT]

It has been my experience that transmission shops know a lot more about the real world of transmissions, than dealers. Especially when you have a hi performance trans.

I would start with a phone call to a trans shop. Try to talk to one of the technicians. Give him a brief description of the problem and see if it triggers a immediate response. Transmission shops get into more varieties of issues than dealers. Dealers are almost always messaging stock issues.