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For those of you dealing with aftermarket ECU swaps, here is a neat little trick for your reverse lockout. Possibly it's been posted here before by others, but here goes....
First, remove this snap ring inside the reverse lockout. Don't worry, there's not pressure behind it. It won't jump out at you.
This is what it looks like after you pull the snap ring.
This heavy spring is the one that causes the resistance. It's basically a miniature strut, and disassembly is the same process. Also, DON'T LOSE THAT LITTLE SPRING I CHASED IT FOR HOURS
That is a C clip holding the assembly together
Compress the spring. I used channel locks. A vise might be easier, so you have two hands.
The C clip is at the top of this picture. Now, find a shorter, weaker spring to insert. You can see here for reference the length I used. It's just a little longer than the assembly.
Here it is, reassembled with the shorter, weaker spring
Put the whole thing back in the body and put the snap ring back in place
I can now compress the plunger with one hand. it still provides some token resistance to keep you from ripping into "7th gear", but not so much resistance that you need to use your knee or your "passenger assist" to help push it over
This would only be beneficial to swaps with short shifter stick handles. It is a lot tougher with a short stick to put in reverse than a long stick. Long shifters have leverage and go into reverse a lot easier and don't need any control box or "solenoid mod". You have to be careful not making it too soft or you could accidently shift/grind into reverse when up shifting into 5th gear or when downshifting from sixth to fifth.
If I had found that thread I would not have bothered with this one. Lol
No problem, I think the more info out there the better.
Originally Posted by dgcustomz
This would only be beneficial to swaps with short shifter stick handles. It is a lot tougher with a short stick to put in reverse than a long stick. Long shifters have leverage and go into reverse a lot easier and don't need any control box or "solenoid mod". You have to be careful not making it too soft or you could accidently shift/grind into reverse when up shifting into 5th gear or when downshifting from sixth to fifth.
I'll have to respectfully disagree with you Mod works great on my T-56, never had a problem with going into reverse on any shift, and I don't go easy on mine when shifting...
It works exactly as I hoped. It doesn't allow me to just rip it into "7th". But I can give it a bit of an extra nudge, and it moves. It reminds me of my Dad's bmw. It just takes a bit of mustard to get it into reverse, but it's not obnoxious, and it's not overly easy.
Hey, Darth. You can operate the solenoid like stock with your Holley ECM if you want.
If the ECM does not have a transmission harness (no trans config possibility), then feed the speed sensor into a Dakota Digital SGI-5 and use the "AC output" option. The AC waveform will fool the ECM into thinking it's a Hall Effect speed sensor and you can use that to configure a virtual speedometer (frequency input configured for speedometer). Then configure a custom output to power the T56 solenoid whenever speed is below 5 mph.
The SGI-5 also has a 4000 Pulse Per Mile output to drive your stock speedometer. And it has a 2000 Pulse Per Mile for cruise control if your car uses that (3rd gens do, I don't know about 4th gens).
Pretty neat trick! I had originally hoped I would be able to use the stock ECU to handle that, but I was forced to go another route. I had also considered the brake light trick, but I'm trying (rather unsuccessfully) to avoid wires going everywhere.
QwkTrip and Darth, I know I'm kind of hijacking this thread but since it did move into Holley ECUs...... I'm a complete newbie to the Holley Dominator.
I've got a Holley Dominator to control my LS376/480 crate motor swapped into my 1991 Fox Body coupe project. I've got a brand new Tremec T56 Magnum installed behind the engine. I want to use my Dominator to control that reverse lock out solenoid. (As of this time, the engine has not been started nor have I ever applied electrical power to the Holley Dominator.)
Question 1. For outputs, Holley says to use a relay if any device requires more than 2 amps of draw. Qwk, do you know if the reverse lockout solenoid requires more than that?
Question 2. My Dominator will accept two types of speed inputs: 1. Frequency/Digital-Hall effect or 2. Inductive speed input.. The T56 Magnum VSS sends out an inductive speed signal. I've researched this and I get confused because I start seeing things like "pulses per mile." Is there a set PPM that the T56 VSS sends out?
The reluctor In the T56 and magnum is 17 teeth. So it is 17 pulses per rotation. You have to set up a VSS input. It is not a standard input like the map sensor is.
As to the lockout, I was trying to avoid tying up an output since mine is an HP. I believe the solenoid is low current, since it is controlled directly by the OE computer. but a quick and dirty 86 relay is cheap to do.
Darth, thank you for that information; 17 pulses per rotation. Once I get into the Holley Dominator software to set up the speed input, I'll then figure out exactly what I need to do. I'm guessing that I may have to do some math with gear ratios and tire circumference, no?
Yes, wiring up a relay for the reverse lockout solenoid wouldn't be a problem. However, I'll try using my Fluke multi meter to measure the solenoid'd amp draw just in case the relay isn't really needed.
The Dominator ECU supports transmission so you can directly wire a GM magnetic pickup speed signal into the ECU (no tricks required) through the J4 connector and enable the transmission config library to unlock those features. But I'm not sure how that works with T56 because it's intended for an automatic transmission that has a speed sensor with 40 pulse per revolution, whereas the T56 has 17 pulse per revolution. Maybe ask as the Holley EFI forum, https://forums.holley.com/forumdispl...-Dominator-EFI
I've never had a Dominator but I'm guessing you could reverse engineer it by looking at the default settings for 4L60E auto trans knowing it has a 40 tooth reluctor inside the transmission (versus T56 with a 17 tooth reluctor). With the HP ECU I had to set up a custom input (Frequency type) and configure it to create a virtual speedometer gauge. I used these values for my T56:
Pulses to Average = 17
Gear Ratio = 3.73 (my real axle ratio)
Tire Diameter = 26 inch (my real tire diameter)
Pulses = 43 pulse per rotation (I tweaked this value until the virtual gauge matched my Garmin GPS speed reading at 60 mph. It just happened to be 43 in my case. It will be something different for you)
Honestly you could set the Pulses field to a fixed value and calibrate using the Gear Ratio field or Tire Diameter field. Either of those three will work for calibration but I liked Gear Ratio and Tire Diameter being a meaningful number and using that weird Pulses field for calibration. It just made more sense to me from a documentation standpoint.
The concept of PPR vs. PPM is,
PPR = Pulses Per Revolution of the reluctor gear inside the transmission. A T56 makes 17 pulses every time the output shaft makes a full turn. A 4L60E makes 40 pulses every revolution of the output shaft.
PPM = Pulse Per Mile. This is mathematical conversion of PPR to how many pulse events occur in a driven mile. This is used to operate older GM electronic speedometers. The speedometers are designed to receive a square wave with a frequency proportional to 4000 Pulse Per Mile. This all depends on what type of speed sender is in the transmission, axle gear ratio, and tire diameter. Each vehicle had custom electronics that did the 4000 PPM calculation for how the car was equipped. In the old days the calibrations were done with gear sets inside the transmission and there was a "speed buffer box" that converted to 4000 PPM square wave for speedometer. In the LS1 days the calibration was done with software settings in the engine controller, and the engine ECU had a special pinout that sent a 4000 PPM signal to the speedometer. The Holley Dominator also has that 4000 PPM pinout capable of operating an older GM electronic speedo but you have to set up the parameters in the software correctly to get it calibrated (so it really delivers 4000 pulse per mile).
Digging into it some more, it appears people will enter the rear gear and tire diameter and then edit the pulses per rotation to make it right
I've been reading that online. Like I posted previously, I haven't even powered up my ECU yet so I'm still in the reading/research phase. I'm trying to learn as much as I can.
QwkTrip, thank you for all of that information. I am a member of the Holley forum and there is a large thread, Installing a VSS Sensor with Holley EFI that I've been trying to read. It's got a lot of information and for a newbie who has never actually worked with the software, that thread is confusing. I'll keep trying to digest it a little at a time. Your post is very helpful. I'm subscribed to this thread so it's easy for me to come back here and read your information if/when I need later in my build.
05-05-2022, 08:30 AM
Reverse Lockout Mod 
