Zombie & GS450h REQ/CLK/MTH/HTM resistance readings

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AdrianB
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Zombie & GS450h REQ/CLK/MTH/HTM resistance readings

Post by AdrianB »

I'm seeing some inconsistent resistance readings across the synchronous serial connections on my Zombieverter. I don’t know what they should be but they look off compared with the ones nkiernan posted recently viewtopic.php?p=49131#p49131.

Here's my readings taken with the connector unplugged and the VCU unpowered.
K readings.jpg
Can anyone suggest what might be wrong? I don’t know how to diagnose this problem. I got my board during the chip shortage and had to add several components so these may be faulty or badly soldered. Everything powers up OK except the inverter and all the spot values look OK too.

REQ & HTM and REQ & CLK look particularly low and when I first put the probes on the reading is in the mid 80s and takes over a minute to climb and stabilise.

Thanks.
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Re: Zombie & GS450h REQ/CLK/MTH/HTM resistance readings

Post by nkiernan »

I'm not sure what to suggest for diagnosing, but just to confirm, are you having the same issue I was having where inverter does not power up and will not spin motors even when VCU has switched 12V relay power to the inverter and HV is seen at inverter also (no inverter whine)? I thought you had the VCU spinning the transmission previously?

Not sure these values are a big issue. When you have VCU connected to inverter, with nothing powered up, are you getting approx 60R between each comms pair? That could be more important?
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Re: Zombie & GS450h REQ/CLK/MTH/HTM resistance readings

Post by AdrianB »

Yep, you’re right nkiernan I did have the transmission spinning but not consistently nor smoothly and now I have a problem which looks similar to yours. All the wiring checks out and the VUC goes into run mode but the inverter doesn’t turn on.

Having reread your excellent thread I’ve been working through these possible solutions:
  • Beefed up the 12+ and ground wiring
  • Tidied up the twisted pair cables. (I’d previously extended them by connecting two short sections together to give me more room on the bench.)
  • Connected a charger to the 12v supply (car battery) to keep the voltage up
So far nothing has worked. The readings between each comms pair look OK. The reading across different pairs are far less consistent than yours. Today’s readings are:
K readings all.jpg
I’m seeing a few odd values in the web interface but these could just be because the inverter isn’t on:
  • Tmphs: 0°C
  • Tmpm: -27.71°C
  • Uaux: 14.4v (battery at 13.4v)
I was working on a couple of other things before the inverter decided to sulk:
  • I wired up the oil pump and initially connected the feedback wire to the VCU instead of the signal wire. Once corrected the pump ran but started to cut in and out. I’m hoping that was just the 12v battery struggling.
  • I had started to wire up the low voltage side of the contactors.
I can’t now remember exactly when in this sequence it stopped working. Updating the software to v1.06A didn’t solve the problem.

As I can’t work out what’s wrong I’ll just keep working through things in the hope of finding the problem. Next I’ll replace the 60V 5A power supply, which is providing my HV, with a few cells from the Lexus hybrid battery.

If anyone has any suggestions, I’m all ears.
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Re: Zombie & GS450h REQ/CLK/MTH/HTM resistance readings

Post by nkiernan »

I'm not sure what to say about the variation in resistance values. Might be best to step your changes back to when they were working, or at least to when it still wasn't consistent and smooth and confirm a base line. Also worth trying to figure out if the inconsistency/smoothness is an issue to resolve before adding in the extras?

From what I've seen, I'd be focusing on the ground wires and inverter/gearbox case grounds direct to 12- first. I do think it was the spike in current draw of the contactors closing that was a factor for me, and my original wiring probably allowed the power to the inverter and/or vcu see the spike at the wrong time! I had to change it back to the original GS450H v4 schematic where the inverter power was direct to the 12+ terminal via a the fuse and relay.
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Re: Zombie & GS450h REQ/CLK/MTH/HTM resistance readings

Post by AdrianB »

OK - things are much better now. I have the transmission spinning smoothly and strongly.

The problem was a weak 12v battery. I thought I’d covered this by also attaching a battery charger but that still wasn’t enough to keep the inverter happy. Supporting the battery with a power supply set to 13.5v did the trick. A new battery is on the shopping list!

I found some other problems but I’ll consider this thread closed as it appears that my REQ/CLK/MTH/HTM resistance readings are all OK.
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