I finally brought my car to life over the past few days. I ran through the gears on the transmission and everything seems to work except for manual low. Now it’s possible I still need to add a little fluid, but does anyone know if low fluid would be a reason for manual low not to work, but every other gear to work? R, D, 3, & 2 are all working when I manually shift to them. THIS IS WHILE THE CAR IS ON JACKSTANDS! I just don't seem to have manual low. While hooked to EFI Live, it shows that I’m always in 2nd gear no matter what position the shift lever is in or what position the transmission lever is in. If I manually turn on Solenoid A using EFI Live with the car off, I can hear it click. If I manually turn on Solenoid B using EFI live with the car off, I DO NOT hear a click. I am using the relay mod made famous by Slow67 and using a regular 4l60e segment. Could my wiring be messed up at the relay?? Now this also has a Jake's D1 transbrake, and 2 step wired up. I tested the 2 step and verified it to be working. I don’t dare test the transbrake if manual low isn’t working, since I obviously have to be in Manual low in order to test it. Like I said, the car is on jackstands still, so it’s not like I’m really beating on it testing things out. Any thoughts or suggestions? Thanks, guys.

 

By not working, what do you mean?

If it locks up as on the transbrake it's because your solenoid state is not low gear. Usually caused by no power to the trans, but could be caused by a wiring or tuning issue.

 

So I start the car, apply brakes, put trans in reverse, release brakes… works… axles turn. Apply brakes, shift to D, release brakes, axles turn. Apply brakes, shift to 3, release brakes, axles turn. Apply brakes, shift to 2, release brakes, axles turn. Apply brakes, shift to 1, release brakes, axles DO NOT turn.

I'm confused as to why EFI Live thinks I'm always in 2nd gear regardless of if I'm in Park, Reverse, Neutral, etc. The transmission has zero miles on it. I can only assume I have screwed up wiring the relay or something. The 2 step wouldn't be interfering right? I mean that isn't technically grounded until I press the activation button, correct? So that ground wouldn't cause an issue if I'm not pressing the button... am I understanding that right? The button definitely works. I can activate the two step in park without any issue. I guess I can disconnect that ground to completely rule it out.

I have no codes present. JTW mentioned it might be the manifold pressure switch... is that a possibility?

Thank you for the quick response, Jake. I appreciate it.

 

It could be the pressure switch. EFI live needs to see the selected gear from the pressure switch so it can command the proper gear.
The 2 step could be interfering.
It's a basic concept of mechanical diagnosis to isolate and eliminate. I would take the 2 step out of the equation while diagnosing but I don't think that's the problem.

 

Okay. I'll try a few things that JTW suggested and remove the 2 step from the equation just to be safe. If it turns out to be the pressure manifold switch... how difficult is that to change out? Another really strange thing is if I use the DVT tool in EFILive with the key on and car in park, and then command 4th, 3rd, 2nd, or 1st, the data tool shows that the "Current Gear" is indeed whatever I command it to be. But if I turn off transmission control activation with the DVT tool in EFILive, it immediately goes back to showing 2nd as the "Current Gear" no matter what gear the shift lever is in. This is a real head scratcher.

 

2nd is default, so if you don't have pressure, that is what it will show, and also what it will command. If you don't have power it will do the same. It sounds like you have power.

Pressure switch is easy to change.

 

Holy hell are you serious?!?! Maybe I'm chasing my tail for nothing. I was doing all this testing of "Current Gear" with the car off. Don't you love helping idiots that don't understand the mechanics of transmissions?

I'll fire the car up and see what "Current Gear" reads in EFILive, then I'll shift through the gears and see what it displays. Assuming it still does the same and first gear doesn't turn the axles, but EFILive shows the correct "Current Gear" when I shift into each gear, what do you think might be the issue at that point? That would eliminate the manifold pressure switch right? Because it's telling the transmission the correct gear that I'm in, right? If 1st gear really wasn't working, wouldn't another gear not work as well? I'm starting to wonder if I am grounding the transbrake somehow all the time without actually pushing the activation button, which happens to be the same button that two-step is wired in to. I know the two-step works as the light illuminates when I press the button. Thanks again, Jake.

 

No problem,
I deal with it EVERY day. I take tech calls for other builders 4L80E's more than I can count. I try to help guys out when I can.

You may be inadvertently grounding the transbrake, and that could be occuring due to the 2 step. That's why it's a good idea to isolate/eliminate.
Modern setups use a lot of electronics to control the engine/trans/datalog/rev limiter/2step/delaybox/N2Ocontroller/traction controller/etc and many times you have to eliminate all the secondary control to determine where the problem actually is.

The D1 transbrake is an awesome design. I say that not because it's mine but from a purely hydraulic standpoint I hit a homerun with that setup because many of the features that I designed into it were an accident and before I knew as much as I do now, and having compared many different t-brake designs from TH400's and other transmissions there are some key features to the design that make it work for the 500 HP guy and the 1500 HP guy with almost the same calibration.

That said,
It will cause a lockup (transbrake activation) in manual low gear if the computer commands anything other than low gear. This is a normal function of the design. It's one of the few drawbacks.
I deal with this as a question on a tech call fairly frequently, particularly when used with our manual control box because when the customer installs the trans, and doesn't hook up the box or power to the box, and the trans is locked up in low gear, they instantly assume something is wrong.
They also seem to think I'm BS'ing them when I try to explain to them that is normal, and tell them how to diagnose the problem.

 

Well I went through my wiring and found out that my 12V switch for the 5 Pin relay was not actually a 12V switch. Thus the 87A pin was always grounded and was either activating the transbrake when shifting to manual low or the transmission was never even seeing manual low. Whatever the case, I found a good 12V switch for the relay... opened up EFI Live and began commanding gears. Per JTW's suggestion, I used a test light to check that each pin was getting the correct signal, and sure enough that was all that was wrong. I can now hear the solenoids clicking in the transmission and all appears to be well. Being as I did all this at roughly 11:30 PM, there was no way I was going to fire up the car and test things out with neighbors that aren't the biggest fan of loud automobiles. I'll post back after firing up the car to report an official success, but I'm pretty positive that things are good to go.

Can't thank Jake and JTW enough. You guys are an asset to this message board. Thank you both for your time and input.

Brad