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How do we manage pop-up headlights using PMU16?

PDM Installation & Configuration

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The PMU/PDM course just came in time for my Toyota MR2 project. I'm in the stage of rebuilding my MR2 for street and sometimes track cars. I am planning to replace most of its relays and fuses.

From my understanding of the Half Bridges & Full Bridges concept, it seems to me I may need to apply this method to manage my Toyota MR2 pop-up headlights.

But how do I wire it? Can I use back the OEM retractable module by supplying the power from the PMU16, and the module plays its role like the H-Bridge?

It seems to be the ECUMasters has a CAN H-Bridge module that I need to buy separately. So it is not something that we can set up by only using the PMU16, right?

I am still very new in the PMU world. And the HP Academy has given me a good learning platform. Looking forward to your guidance and good discussion here. Below is the wiring diagram of Toyota MR2 pop-up headlights for reference


[img="blob:https://www.hpacademy.com/9c8eac3f-a04c-4cfb-bf99-7d067bbd5bd4" alt="" alt="" ]

While I'm not super familiar with MR2 headlights, I am doing a similar project with my FC3S. Rx7 uses a completely different (old) school of thought but for the sake of discussion lets dissect both.

If I understand that diagram correctly, an H bridge is not the route I would go. My Rx7 headlight motor actually spins the same direction wether going up or down, the difference is where it stops. I imagine the MR2 is the same, as the diagram shows no way to reverse the motor, one side is always connected to ground. Toyota did us no favours and left the box that controls this blank, so testing to confirm will be a very good idea. So we move our attention to the limit switches on T2 and T1,3. 2 is the common, and I'm guessing 3 is down position and 1 is up (based on the fact that de-energized state the lights would be down).

I would wire them separately for each motor, as they wont stop in the same place each time as each other. T2 connected to ground (same place as the PMU's) and T1 to PMU input (A), T3 to a different PMU input(B). This allows the PMU to know when the light is in X position and can stop power to the motor.

Ground T5 and wire T4 to a PMU output (X). I can type out a logic statement to operate this but only if you would like me to lol.

You can do this with an H bridge or 2 outputs and some diodes but thats even more complicated and unnecessary in my opinion. It would be cool if manufacturers built in H bridges into power modules, especially for E wastegates. I get people asking for a PMU to do power windows all the time and my advice is use 1 output to power the windows and switches (or switch relay combo) to do the control. The PMU can do it but it eats up outputs that are better used for more essential devices.

Just for fun (and in the hope that someone has a better idea) I'll run through the FC Rxy (see attachment). These motors have a relay hanging off of them and the whole thing is pretty integrated, so for the sake of easy replacement I'm going to stick with how the factory wired the motors.

Power for the motor is fed on W/G, and ground is B. Once again this never changes, the motor spins 180 to go up and the remaining 180 to go down. The circle things on the diagram in the motor assembly with UP and DOWN beside them are the limit switches. So when you use the headlight switch to give power to the R/L "UP" wire, it throws the relay in the motor assembly and the motor spins until the limit switch breaks the relay's coil power. Then to go down the process simply repeats on the R/Y "DOWN" wire.

At the moment I am planning to use 2 outputs to do this, one for up and one for down but both powering the motor and a diode preventing back feeding on the output not being used. I am pretty tight on outputs though so I may end up using the switch as Mazda intended and just powering the motors off one output.

Hope that helps further your understanding. Shout out to Toyota for better electrical design and diagrams then Mazda lol.

Attached Files
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Hi Aqmar,

I have an MR2 track car that I wired once with a new fusebox and relays and am now working on switching to an AIM PDM32. I managed to get the popup lights working in my first system after much trial and error - that retract relay box houses some magic elves I think!

Anyway, applying a GROUND to B-6 in your diagram causes the lights to retract. Applying a +12v to B-8 pops the lights up. B-3 also needs to see +12v for all of this to happen i.e. no +12v, no retract when ground applied. This is how my car is wired currently using two relays and a toggle switch (2 relays required as one switches +12v while the other switches the ground).

I too would like to replace all of this, including the retract relay, with just the PDM. I'm sure it's possible, just need to get my head around it...

Hi Mark, Did you ever get the popup lights working through the PDM I'm also trying to do this on my MR2!

Hi Mark, Did you ever get the popup lights working through the PDM I'm also trying to do this on my MR2!

[img="blob:https://www.hpacademy.com/b2c0d59e-2bc4-4de2-abd8-05d62b638cd1" alt="" alt="" ]Thanks, Mark and Tyson, for the idea shared. I wish to share my planning here. Please note that I have not thoroughly tested this proposal yet and still working on the rest of the car wiring.

Attached is the wiring schematic for MR2 pop-up headlights that I refer to for this discussion. I hope this may also help Reece in his setup.

Based on these schematic diagrams relay needs three inputs to operate the retractable headlight motor. We name it pins #3 (B-3), #6 (B-6) and #8 (B-8). Also attached is the socket connector picture of the retractable headlight relay.

[img="blob:https://www.hpacademy.com/14ae5b41-9774-4e45-8519-d9649507a2ef" alt="" alt="" ]Mark has explained it well based on his finding. We can summarise it as below:

- Voltage is applied at all times to Pin #3 of the retract control relay.

- When the signal is sent to Pin #6 trigger, the motor retracts up

- When the signal is sent to Pin #8, trigger the motor to retract up and the headlights ON.

I BELIEVE #8 is triggered when you are ON the Hi-Beam momentarily

Therefore I suggest using a 25amp output pin to #3, a 15amp output pin to #6 and an input pin from the steering light switch button. If you realise, I did not connect the PMU to pin #8. Technically, if the PMU16 is already controlling the hi-beam, it should no longer need pin #8. When a hi-beam flash signal is sent, we can create a logic to retract up and down the retractable motor. Attached is the example. Please feel free to comment. I still think that my planning here got a lot to improve.

For Reece, as I am using MR2 SW20, I have tried my best to explore utilising the PMU16 and what I can say is that 1 unit of PMU16 is just barely there. I want to control the headlights, retractable motor, tail/parking lights, indicator lights, radiator fan, reverse light, boost solenoid (for 3SGTE), VVT (for 2GR), starter solenoid, CanLambda, engine bay fan, Power Steering motor, AC compressor, fuel injector, coil on plug, fog lights, fuel pump, alternator field and your standalone ECU, then 1 PMU16 won't be enough. But that discussion we leave for some other thread-specific discussion on that matter.

Attached Files

Hi Tyson,

For your information, i have fully tested using the MR2 retractable light relay match with PMU16. IT WORKS like how I explained above.

Now I thought of trying ur suggestion. I'm interested to see the logic statement if you don't mind sharing it. Would that be ok?

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