My GQ manual torque converter lock up system (lotts of photos)

There's lots of info for GU manual torque converter lock ups, but I haven't seen a step by step write up for a GQ here, so I thought I'd share mine, and knowing that some of the earlier members of the site really love photos (and I do too), I took lots.

A huge thanks must go to Chaz www.chaz.yellowfoot.org/Lockup Trans Switch.htm, without him this may never have happened. I used his wiring diagram (made for a GU, but easy to adapt)

http://www.nissanpatrol.com.au/forums/

and then he was the one who guessed the stupid mistake I'd made, which caused me so much grief when I first tried to use it. The only modifications I made to his wiring diagram were with the numbering. The TCU terminal numbering on a GQ is different to a GU. Using a GQ wiring chart, the wire on our GQ Transmission Control Unit which sends power to the lock up solenoid is number 22 (a grey wire with a red stripe) and the one that sends power to the inhibitor switch (for the P/N lock out relay) is number 19 and is a white wire. The other numbers I changed were 85 and 86 on the brake light relay, and this was just to make terminal 86 the earth terminal for all of my relays (on my relay sockets #86 is a blue wire).

After deciding to go with a system which cut out when the brakes were applied, and had protection from being accidentally activated when in park or neutral (Chaz's system), the next step was to work out where to fit the various parts.


The photos will tell most of the story of what and how.


Here are most of the parts needed for the system. Four relays, as per the wiring diagram. One to do the actual job of engaging the transmissions lock up solenoid, one to prevent the system from activating when the transmission is in park or neutral, one to deactivate the system when you apply the brakes, and the fourth one working with the brake one as a latching relay. An on off switch with a built in LED. A momentary switch, some wire, some crimps, a flashing LED, an enlargement of Chaz's diagram, and a rough outline of how I wanted the new wiring harness to run. There are also some optional extras. Heat shrink, some 3 in 1 connectors, and a plastic box from Jaycar. The rest of the stuff in the organizer box is mostly for when I upgrade our lights and horn.
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The switch to arm the system, and the flashing led to warn that it's active, both needed to be in clear view, and I didn't want to cut into the dash to fit them. The last vacant switch hole below the instrument panel was the obvious place for the switch. The best spot I could see for the flashing LED was in the hole down from the steering wheel on the left.
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With a bit of searching I found that a Narva 63021BL switch was ideal because it was the right size for the hole, and has a red LED built into it. If you don't like red, they have LEDs in other colours too. The power for this switch comes from a cable on the back of the fuse panel which is live when the key is on, and runs via a 10amp fuse to the switch.
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In our GQ, (carby model) there was a huge cavity under the dash, next to the glove box, up above the TCU. With this in mind I decided to put all of the relays into a box and to put it into that space. This meant that I had to run three wires from the switches (one from the main switch, one from the momentary foot switch, and one from the brake light switch) on the drivers side, across under the dash, to the relays on the passenger side. This shot is looking in the hole where the glove box goes.
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I got a heap of sockets for the relays on ebay, way cheaper than anywhere else I'd seen them.
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Twitched the wires together as per Chaz's wiring diagram.
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Tested it like that, and it worked first go.
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Cut the excess wire out, and soldered the remaining ones together, heat shrinking them as I went.
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Here they are, screwed into the box, with the mounting bracket fitted to the outside.
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I used proper connectors on the wires outside the box, because I didn't want to risk any confusion about which wire went where if it needed to be taken out at some later stage. The box has six wires coming from it, three to the switches on the drivers side, and three going down to join into the wires near the TCU.
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Making this bracket should've been dead easy, but it's really hard to measure inside the dash. Took a fair bit of trial and error. I cut it as close as I could, screwed it to the box, tested how it fit, cut it a bit smaller, tested again, then bent it a bit, then held it in place and marked where to drill the mounting holes in it.
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Even finding which bolts to use took some doing. I had to use the holes which were already there because I don't have a right angle drill attachment. These are really short and fat.
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In the end it all worked. Here's the bracket in place.
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Here's the relay box screwed to the bracket, and the blue cable across the middle of the picture is the heat shrink with the three wires coming from the switches to the relays.
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There's very little room to work on the wires of the Transmission Control Unit (TCU). Unscrewing it off the side panel does give a bit of extra space, but not much. I used a test light to make sure I was cutting into the right wires. Bit tricky at 100km/h, but with some help from my son it all worked out in the end. I saw a tip since then, suggesting to stick sewing pins through the wires you want to test, and then using your test light on the pins. Wish I read that before I did this part of the project.
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This is Nissan's numbering of the terminals on the GQ TCU. It was correct for our Trol.
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The flashing LED was an annoying mistake I made. Buying it as an individual component wasn't a good idea, I then had to work out what size resistor to use so it wouldn't burn out.
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Next comes the challenge of insulating it. Some insulation off other wires, and some heat shrink was the best I could come up with. There are lots of photos of this, as a warning not to do it from individual components like I did.
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Opinions vary as the whether resistors should be covered in heat shrink. I figured it may overheat if covered, and then I'd have the frustration of replacing it. With leaving it uncovered, the biggest risk is that it might hit on something and blow a fuse. I attached two wires to the positive side of the LED to make it easy to connect it to the momentary foot switch and to the hold in relay.
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This plug was already filling a hole in the dash. The LED fitted inside it just right, and I just drilled a hole for the LED to stick through it, then glued the LED into it with silicone.
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When I went to take power from the brake light switch to run the cut out relay, I found a real mess. One side of the switch is permanently live, the other side is only live when you press the pedal. Our aftermarket cruise control takes power from both sides of the switch, and it's obviously had electric trailer brakes attached to it previously too. As I was trying to sort this mess out, I broke one of the wires off the factory connector. In the end the easiest solution was to remove the connector, pull the terminals out of it, and connect new wires onto them. While I was doing that I added some extra branches to the new wires to make it easy to connect the various accessories to them. My next electrical job on the Trol is to put an electric brake controller in it again, so having the wire there ready to go will make that a lot easier.
This is the connector rewired and ready to go back in.
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The best momentary foot switch I could find was one designed for an electric guitar sound box. I hope it lasts, though it wont be too hard to replace if I have to, just resolder the wires and wrap it in heat shrink again.
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The bracket for the foot switch is just screwed onto the strip which runs up the side of the foot rest. With the switch here I shouldn't accidentally hit it, and I just have to roll my foot forward over the foot rest a bit to click on it.
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This shot shows what I see when the system is active.
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I made a few mistakes along the way. Buying the wrong type of flashing LED was an annoying one, also I should've used more colours of wires. For example when I ran the three long wires across under the dash, I had to put power into each one on the drivers end to work out where they had to connect to on the relay box. If they were three different colours I would've known which was which straight away. Same with the wire running from the TCU to the lock up solenoid. It is grey with a red stripe, so after cutting it I used grey wire to extend both ends of it up to the relays. If these were different colours, it may have reminded me that only one of these now goes to the TCU, the other goes to the transmission's lock up solenoid.

When I ordered heat shrink I could've done better with the sizes. Most of it was okay, I had plenty of really thin stuff, and enough 6mm and 25mm, but didn't realise I'd need something in between.I was able to buy a short piece of 20mm in town, but a length of 15mm would've been good.

The biggest mistake I made may have been prevented if I'd used more wire colours. After getting all the other other wiring right, I connected the last two wires to the wrong place. They were both grey, and I forgot that one was coming from the TCU and the other was going to the transmission. I swapped them over and fed power from the relays into the TCU instead of into the transmission, and now it looks like I've wrecked that part of the TCU. It could've been a lot worse, if it'd damaged the torque converter clutch, the transmission would've had to come out to fix it, and I really don't need that. As is I just have to lock the converter manually all of the time, as the TCU can't keep it locked up, it keeps cutting in and out.

I've done a 1300km trip (Sydney and back, mostly on the Hume Fwy) towing a 6 x 8 trailer since I fitted my lock up system, and it worked really well.

Feel free to ask any questions. For general torque converter lock up stuff, there'll be plenty here who can help. For specifics about my system, I'm happy to explain in more detail if needed.

How does it go changing gears while locked up? or is it something that you should only lock up when manually selected a gear?

Whilst the Park/neutral relay stops the lockup while either park or neutral is selected, what happens if you are stationary in neutral, with the lock up activated, then select drive? wouldnt that cause it to stall?

Quote:

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Originally Posted by teno45

How does it go changing gears while locked up? or is it something that you should only lock up when manually selected a gear?

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It kicks down from 4th to 3rd really well. Going up longish but not steep hills (at 110 km/h) I made it kick down and then kept it in 3rd by turning off OD. Going back up to 4th took a bit of coordination with the accelerator pedal to do it smoothly.

Quote:

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Originally Posted by teno45

Whilst the Park/neutral relay stops the lockup while either park or neutral is selected, what happens if you are stationary in neutral, with the lock up activated, then select drive? wouldnt that cause it to stall?

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In a GU that may be the case. In a GQ with a standard valve body, I don't think the TC can lock at all in 1st gear, so it wouldn't cut in till you hit second.

Excellent write up ripper! And a job very well done. Shame about the TCU, but like most of us that have the system fitted, you'll always control it manually from now on.

I also got sick of the red flashing LED and replaced it with a solid green LED. Much easier on the eyes.

Originally Posted by teno45
Whilst the Park/neutral relay stops the lockup while either park or neutral is selected, what happens if you are stationary in neutral, with the lock up activated, then select drive? wouldnt that cause it to stall?

If you allow it to lock in Park or Neutral, you'll hear a very loud and evil noise comming from the transmission. If you leave it in that state for more than a few seconds, you will have done some very expensive damage. That saftey feature is there for a very good reason and should be considered. A few people that didn't fit it, soon did after accidentally locking it while stationary.

Thanks Chaz. Hopefully my flashing LED is low enough in the dash to never become a nuisance.

With teno45's question, I thought he was asking about a system which has P/N protection on it, and whether you could still stall the engine when you shift from P or N to drive.

Quote:

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Originally Posted by ripper

Thanks Chaz. Hopefully my flashing LED is low enough in the dash to never become a nuisance.

With teno45's question, I thought he was asking about a system which has P/N protection on it, and whether you could still stall the engine when you shift from P or N to drive.

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I misunderstood teno45’s question. The answer is that it can’t lock, so nothing happens unless you have your foot on the switch as you take it out of Park. Then it will stall the car.

Great thread ripper, you've done an excellent job!
I'm certainly going to do this to my TB42E wagon. I saw them talking about it on the 4x4 TV show the other day & they were saying how good it is for steep decents as it gives you engine braking like a manual.
Does the hold switch only hold it locked while it's held down/ depressed?

Thanks Acko.

Quote:

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Originally Posted by Acko

Does the hold switch only hold it locked while it's held down/ depressed?

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No, it stays locked until you use the brakes or manually switch it off. For steep decents you need to hold the momentary switch down while you brake. Because of this, positioning the switch just above the footrest works really well.

Ok cool, I was wondering what the point was but all makes sense now.
Thank you. :)