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MS3 PNP Pro VVT non-functional

 
Old 04-03-2019, 12:50 AM
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Default MS3 PNP Pro VVT non-functional

A few weeks ago I was trying to diagnose a weird noise coming from the engine. When I disconnected the VVT solenoid, the connector crumbled apart and the pins touched, shorting the ECU and the engine shut off. I opened up the MS to find that one of the traces on the lower board had lifted and broken, causing the ECU to become non-functional. I had a local electronics repair shop fix it, they applied a small sliver of solder to the wire trace, and boom, it works now.

I just completed doing a complete timing belt overhaul and rebuilt my entire VVT system. All new o-rings, gaskets, crush washers, the works. Guess what, my VVT system actually seems to work now! Except well... It works TOO well. In fact, TunerStudio shows 45 degrees of intake cam advance, which goes straight to 0 when the VVT solenoid is disconnected. The car also idles REALLY bad.

I tested the ECU by putting it into Output Test Mode and hooked up a multimeter to the VVT connector.

When High Current Out 1 is forced ON, the meter reads 12.6V.
When HCO 1 is forced OFF, the meter reads 12.6V.

As far as I know, the HCO are ground triggers, meaning that 12V is constantly supplied to whatever requires them and the ECU provides a ground for them to work. Given the above scenario, is it possible that I have damaged the HCO 1 driver and all it does it ground out instead of cycling on and off?
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Old 04-03-2019, 03:30 AM
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Yes, the driver is gone.
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Originally Posted by ninerwfo View Post
The “into to megasquirt thread” mentions that the MS3 basic has 5 inputs with built in pull up resistors - and I was just wondering why it would have so many, while the MS3Pro PnP has just 2 (with no pull ups?)
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Old 04-04-2019, 12:50 AM
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Originally Posted by Reverant View Post
Yes, the driver is gone.


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Old 04-04-2019, 12:51 AM
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DIYAT quoted me $150 + parts ($75 diagnostic, $75 repair) to fix it. I wonder if I can replace the transistor myself?

EDIT 1: Took box out of car and opened it up. I've got decent soldering skills, but I'm not willing to risk further damaging the board without a proper soldering station meant for circuit boards. Lots of small components tightly packed next to each other. When it comes to electronics repair, not knowing what to do or having the proper equipment can make a bad situation even worse.

Also, Matt over at DIYAT said that when these fail, it usually blows up in some spectacular fashion and leaves visible damage to the board, but my MS3Pro board is pristine. No visible damage or burn marks. What gives? Did the failed trace on the interface board act as a sort of fuse that protected the rest of the board?

Last edited by dsamani; 04-04-2019 at 01:18 AM.
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