Mytqik's TB45 to TD42 wiring guide

48019 Views 104 Replies 21 Participants Last post by Jjjag2099, 4 mo ago

mytqik

Discussion Starter · Dec 11, 2014

I am I the process of converting my GU Ti TB45 auto over to a TD42 auto. There is a link in my signature to my build thread for more information on the mechanical side of things.

Everything below is to suit a 1994 black top GQ TD42 into a 1998 GU Ti TB45. Please double check everything before following my lead

As I do the wiring I thought I would document it, save anyone else the hours that I have trawled over GQ & GU wiring diagrams.

Starter:
The heavy Black/red (50mm2) main power cable can be re-used. I re-lugged it to suit my new battery terminals better.
The White/red (6mm2) wire will need to have the blade plug cut off the end and a ring crimped on.

Alternator:
The alternator and P/S pump are on different sides from the TB to the TD, therefore the TB wiring will need to be extended to suit.
I used my old 50mm2 winch power cable in place of the *********** cable that runs from the ALT to the fuse box.
The black wire needs to be extended with a ring crimped on the end.
I found that the plug for the yellow/red & yellow/black is actually the same plug/pin outs as the TD42 alt, so I just extended these 2 wires and re-used the TB45 plug.

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xhxrsix

· #21 · Jan 4, 2015

Nah I haven't tackled the tacho yet, most of the time I do things the fastest easiest way and then refine it from there haha, so its still on the to-do list

For the glow plugs I've used some wiring out of a GQ, but it already had a different relay in it. So its wired up to a push button inside. Not going to bother with a timer unless it gets annoying later, only really need it at first start up now anyway.

AKO89

· #22 · Mar 10, 2015

Tacho.
It will work, all you need to do is connect the blue wire from the sender to the YB (yellow with black trace) wire at the back of the dash, it can also be found in the middle of the 3 white plugs under the dash above the clutch pedal. then connect the other wire of the sensor to an earth.

the sensor is 6cyl and so is the dash. it will work with out any modules ect.

The other thing I didn't see in the previous post was about the senders on the motor. you need to make sure you use the sensors from the TB45 on the TD42 as they match the dash. they all screw straight into the TD with out issue.

mytqik

Discussion Starter · #23 · Mar 10, 2015

AKO89 said:
Tacho.
It will work, all you need to do is connect the blue wire from the sender to the YB (yellow with black trace) wire at the back of the dash, it can also be found in the middle of the 3 white plugs under the dash above the clutch pedal. then connect the other wire of the sensor to an earth.

the sensor is 6cyl and so is the dash. it will work with out any modules ect.

The other thing I didn't see in the previous post was about the senders on the motor. you need to make sure you use the sensors from the TB45 on the TD42 as they match the dash. they all screw straight into the TD with out issue.

AKO89 thanks for the input into getting the tacho working. Have you tried this? The only reason I ask is that according to my workshop manual, the Petrol tacho is expecting a 0-5V DC square wave 360 pulses per revolution, and the diesel tacho sensor outputs an AC since wave with 8 peaks per revolution. It looked at the 2 different wave forms and "frequency" and could not come up with a way to upscale the 8 pulses to 360 pulses.

You are correct about using the TB45 sensors! The sensors are even different between GQ & GU! I was wondering why my temp gauge was all over the place when I first hooked it up, but after swapping to a GU sensor it was all good.

I used the GQ oil pressure switch, the oil light goes out almost instantly after the engine fires.

I also swapped the 2nd temp sensor (used by the glow plug controller) to a temperature switch to control the thrmo fans. Need to take some photos and do a write up on this too!

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AKO89

· #24 · Mar 10, 2015

mytqik said:
AKO89 thanks for the input into getting the tacho working. Have you tried this? The only reason I ask is that according to my workshop manual, the Petrol tacho is expecting a 0-5V DC square wave 360 pulses per revolution, and the diesel tacho sensor outputs an AC since wave with 8 peaks per revolution. It looked at the 2 different wave forms and "frequency" and could not come up with a way to upscale the 8 pulses to 360 pulses.

You are correct about using the TB45 sensors! The sensors are even different between GQ & GU! I was wondering why my temp gauge was all over the place when I first hooked it up, but after swapping to a GU sensor it was all good.

I used the GQ oil pressure switch, the oil light goes out almost instantly after the engine fires.

I also swapped the 2nd temp sensor (used by the glow plug controller) to a temperature switch to control the thrmo fans. Need to take some photos and do a write up on this too!

I sure did try it.

I did a conversion on a mates tb45. we put off looking into the tacho for about 12 months as we thought it would be a night mare. and well its not. its as simple as I explained above. if you wanted to get real clever you could get a 2.8 cluster and pull it apart and put the tacho section into yours. then you know they are exact. but it works otherwise.

Im currently working on getting my tacho going in my CRD to td conversion. the logic is simple. will see how it goes

xhxrsix

· #25 · May 24, 2015

Any progress on this? I have connected my tacho as above, wired directly to the cluster.. It works well but only above 1000rpm... (GQ TD42 into GU 4.5)

outback

· #26 · May 25, 2015

AKO89 said:
I sure did try it.

I did a conversion on a mates tb45. we put off looking into the tacho for about 12 months as we thought it would be a night mare. and well its not. its as simple as I explained above. if you wanted to get real clever you could get a 2.8 cluster and pull it apart and put the tacho section into yours. then you know they are exact. but it works otherwise.

Im currently working on getting my tacho going in my CRD to td conversion. the logic is simple. will see how it goes

That wont work as the taco gauge is a slave and driven by the speedo control module.

Works with GQ TB to TD cluster but not GU

JFF45

· #27 · May 30, 2015

I'd be interested to know if you got the A/C working with the TI LCD module. I understand you removed the rear A/C because of your dump pipe.

Also interested to know what TCU you finally used.

Thanks for all the info you've supplied throughout your various threads.

I'm about to start the same conversion on the same model, same colour too, retaining the auto trans which I rebuilt myself to Q45 spec with Nomad valve body.

xhxrsix

· #28 · May 31, 2015

My aircon works basically as normal and I've just bypassed the ECU..

JFF45

· #29 · May 31, 2015

xhxrsix said:
My aircon works basically as normal and I've just bypassed the ECU..

Great thanks, I see you also have a Ti. So climate control functions as before?

xhxrsix

· #30 · Jun 1, 2015

Yep it all works normally, only thing im not sure of is when the aircon is on and ign turned to on (engine not running) the aircon fan will come on, can't remember if it used to or if the engine had to be running? Either way it doesn't matter in the end!
Rear aircon all works too and I've kept it all even running a high mount turbo and 3.5inch dump pipe.

JFF45

· #31 · Jun 1, 2015

I think the fan runs with ignition on if A/C is switched on. I'll check tomorrow.

Did you get the tachometer working too?

xhxrsix

· #32 · Jun 1, 2015

Tacho works and seems accurate but only after 1000rpm, before that it doesn't a work at all. Haven't looked into it yet!

Reactions: 1

JFF45

· #33 · Jun 1, 2015

The TB45E ECU controls the A/C kicking in when engine gets too hot (can't remember temp) and also controls the A/C cutout when too hot.
The TD42, I believe, used sensors in the radiator to achieve both those tasks.
Did you implement that?

Also the TB45E has a 2nd fan circuit for the right side of the radiator. The 2 pin plug is there taped up and the relay slot behind the battery is also wired up. Just need to pop a relay in there. The earth wire that activates that relay is connected to the ECU but no idea at what temp it switches it.
As the TD42 seem to have a reputation for not always keeping cool, I might add the 2nd fan to a manual control. I have a big Davies Craig trans cooler on that side so a fan might also come in handy for that..

mytqik

Discussion Starter · #34 · Jun 3, 2015

JFF45 said:
I'd be interested to know if you got the A/C working with the TI LCD module. I understand you removed the rear A/C because of your dump pipe.

Also interested to know what TCU you finally used.

Thanks for all the info you've supplied throughout your various threads.

I'm about to start the same conversion on the same model, same colour too, retaining the auto trans which I rebuilt myself to Q45 spec with Nomad valve body.

The AC is working great, now that I have got the custom AC lines made up. I am only running the front AC unit, I removed the rear AC unit now.

I am still running the TB45 TCU, it holds the shifts a bit long under full throttle, but shifts fine on light throttle. I am in two minds on what to do long term. Part of me wants to put in the GQ TCU, and remove the TB45 ECU. The other part wants to change the valvebody over to a Kewdale manualised one with a ratchet shifter and remove all of the electronics all together.

Glad I could help out. I know how hard it was to find solid information when I was planning my conversion. I spent hundreds of hours reading forums, workshop manuals and wiring diagrams before I started. Be interested to follow your build thread.

Reactions: 1

JFF45

· #35 · Jun 3, 2015

Ah, that's ineteresting.. Do you still have the ECU connected? I've been hoping I could find a way to retain the original TCU/ECU combo even if I have to generate some false signals somehow to keep it happy. I thought maybe the redundant engine check light could used for water in fuel signal.

I have my TC lockup running from a Jaycar frequency switch and it gets its VSS from pin 40 on the ECU so keeping the ECU would save me some head scratching.
Other big advantage is that I have a spare TB45E TCU and ECU although the ECU was basically useless up to now because of the NATS coding required. Now I can keep it as a spare.

I have the Nomad valve body. I'm not interested in changing gears. I'm a 70 year old grandfather and can't remember the last time I changed gears

. Oh wait, I do have a manual gearbox on my old 2 cylinder Kubota tractor..

No way would I get rid of the rear A/C. In really hot weather, it helps cool the interior much faster.
Also interested to see how the cruise control will work out.

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JFF45

· #36 · Jun 3, 2015

xhxrsix said:
Tacho works and seems accurate but only after 1000rpm, before that it doesn't a work at all. Haven't looked into it yet!

I'm not sure how this is going to work out for me. The 24v TD42T import engine I bought doesn't have the tacho signal sensor on the front of the engine. It's a 2 wire magnet bolted in just under the IP gear.

mytqik

Discussion Starter · #37 · Jun 3, 2015

I still have the TB45 ECU connected. I tried to run it with the ECU unplugged, but the TCU goes into limp mode (stays in 3rd). I have had to play around with the throttle position sensor to get it to change gears, very easy to do.

Did your TD42T come with a throttle position sensor on the IP?? It should have a 6pin plug, and attaches to the throttle shaft. Does the IP also have the NATS solenoid attached to the back of it?

Don't forget to change the IP fuel solenoid with a 12V one

Do you have any more info on the Jaycar frequency switch to control the TC lockup??

The NATS system becomes redundant after the conversion, as NATS talks to the ECU (which then controls if the TB45 starts). I have wired the TD42 to not use the ECU to start.

As a side note, the fuel injectors are wired directly to the ECU power circuit, with the earth "switched" internally via the ECU. I unwrapped my entire loom from the ECU forward, and then pulled the 6 injector positive wires back through the firewall. This gives me 6 powered circuits that are switched via "on" for internal accessories.

Can understand wanting to keep the rear AC. It does require the use of a non-standard exhaust manifold, which moves the dump pipe forward. That means a custom exhaust needs to be fabricated, which I didn't want to do. I used all off the shelf parts, which makes getting spares easier/quicker.

Cruise control does have its own controller, and doesn't require the ECU, however it does communicate with the TCU. I haven't attempted to make it work yet, that is definately a rainy day project!!

JFF45 said:
Ah, that's ineteresting.. Do you still have the ECU connected? I've been hoping I could find a way to retain the original TCU/ECU combo even if I have to generate some false signals somehow to keep it happy. I thought maybe the redundant engine check light could used for water in fuel signal.

I have my TC lockup running from a Jaycar frequency switch and it gets its VSS from pin 40 on the ECU so keeping the ECU would save me some head scratching.
Other big advantage is that I have a spare TB45E TCU and ECU although the ECU was basically useless up to now because of the NATS coding required. Now I can keep it as a spare.

I have the Nomad valve body. I'm not interested in changing gears. I'm a 70 year old grandfather and can't remember the last time I changed gears . Oh wait, I do have a manual gearbox on my old 2 cylinder Kubota tractor..

No way would I get rid of the rear A/C. In really hot weather, it helps cool the interior much faster.
Also interested to see how the cruise control will work out.

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JFF45

· #38 · Jun 4, 2015

Some excellent info there! Means I don't need to look for a different TCU.

yes, I have a list of 12v items I need to get, already ordered the 12v glow plugs.

The engine I have is a factory turbo black top with the mechanical pump, no electronics. It was an auto so I have the original flexplate and the TPS on the pump. Being turbo, it has the boost compensation on the pump.
That was pretty smart with the injector trigger wires. I'm reasonably familiar with the ECU, I have an Xede piggyback currently wired into it.
I was hoping to find a method of supplying the ECU with a signal to simulate the tach signal from the distributor thinking that might help with the tacho issue.

mytqik

Discussion Starter · #39 · Jun 4, 2015

I have covered in this thread, which wire colours/pins you will need to adapt the TPS on the IP to the TB45 wiring.

That was a pretty good engine to pickup! Did you source it locally or import it from Japan yourself??

Great minds about the Tacho!!!....I looked into the tacho issue, even commissioned 2 different companies to build a converter box, in the end it got too hard & costly.

The main drama is that the distributor puts out 2 different signals, both squarewave 0-5V.
1 signal is for every degree of rotation of the engine (360 pulses per rpm), this one is used for the tacho,
The other is every 60d with every 6th pulse being a longer duration, this longer duration pulse signals TDC to the ECU. (this 2nd pulse is used as reference, it also uses this pulse to confirm the engine is rotating and therefore hold the fuel pump and AC relay in).

The TD42 tacho sender puts out a sine wave with 8 peaks per rpm. Even if you chop the sine wave into a pure DC wave, trying to multiply 8 pulses up to 360 is extremely hard (IE very very very very hard and costly).

It is ok for a constant RPM, can easily build a pulse generator to fire off 45 pulses at a set frequency before the next batch of 45 pulses is required to start. But as the engine RPM rises and falls the frequency of the 45 pulses needs to change as well, otherwise you will have overlapping pulses.

I then tried making it work at max rpm and having a gap between the end of the first batch and the start of the second batch. This results in the correct number of pulses per RPM. However the tacho is PWM and relies on the correct width between the pulses. Having the massive gap between pulses made the tacho really jumpy at low RPM, but smoothed out at higher rpm.

The far cheaper option is to buy a TD42 GU dash.

Let me know if this all makes sense??

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JFF45

· #40 · Jun 4, 2015

Yes it makes sense and also tells me that it's now not worth spending time with that idea. It's not at the top of the priority list anyway.

Frequency switch for TC lockup. Here's the schema I did for it.
It removes the need to have the safety relay to prevent locking in Park.

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