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In my case, I have 5 bad channels (out of 6 on the FET driver chip) at once. That indicates either the TPIC46L02 driver or the MC68377 CPU. It's unlikely for 5 discrete power FETs to all fail simultaneously. If there were a TPIC2601 instead of the FETs, that would be the prime suspect.

In your case, you have one or (maybe) two bad channels, so it might be worth checking those FETs.

The bypass capacitors will decrease in value as they age, unless they fail hard and short, but that would take out much more of the ECU than either of us is seeing. If the caps are so aged their values have become too small, you would likely see (with increasing frequency) internal ECU error codes, as things in there got noisier, electrically. FWIW, at design time, you usually pick a cap value larger (up to 10X in some cases) than required initially to anticipate this aging and compensate for parts tolerances.
 

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By the way, do u know what that 6th channel is used for? I couldnt trace it, so i assumed its not used for anything!
 

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I have no idea either, but I haven't traced everything yet. :( I was thinking it might be the boost pressure valve or one of the evap cannister valves, if the channel is actually used.
 

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I got the chips in from TI, and once I get the binaries read from the bad ECU and the replacement spare that I intend to tune, I'll have a go at the bad one. While it's apart, I'll do some tracing, because I'm intrigued by what the MC68F375 (MCP) is doing besides the throttle body. The spare even came with connectors, so I have a bench setup now.

It took less CPU power to land on the moon than it does to run this motor. 👃
 

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😂😂😂
I want to wish u luck on replacing that chip, as its pain in a** to remove, once its removed its easy to put the new one, i suggest a heat gun to around 350c in addition to a soldering gun on the pins, so might need 3 hands 😂😂😂.
 

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Ya, flux, soldering iron + solder wick, more flux, and then hot air soldering tool is a good way to get the old one off. Did I mention flux? 😂😂😂 Plus good tweezers and picks.

EDIT: Also ordered the textbook for doing the tune 😂😂😂
 

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Some progress with a couple of tangents. I'm working on a disassembler for 683XX CPUs like in our ECUs, and got pretty busy with the US holidays.

I just ordered the hot air soldering station because I was pretty OCD about getting a decent one (and I only needed hot air, I have two Weller stations already). I read the other ECUs I have today, so I can take apart and trace on the bad one over the weekend. Needed to do that first in case the good one I bought wasn't and I needed to return it. Then when the hot air gun gets here I'll do the chip change.
 

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OK, so I'm finally clear to take apart the bad ECU, now that I've cloned it into the good one I got. Is it my imagination, or are the two halves welded together at the edge?
 

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5070E82C-111F-46DA-B877-B4B00BCC57F1.jpeg
This is how its opened, one side only .. and the cover is one piece that goes around the frame like a U .
 

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Thanks. At least I can bend the cover instead of grinding off a weld. I figured that was the edge where the flexible PC connecting the boards was hanging.
 

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UPDATE: I changed the TPIC46L02 and tried that ECU with stock tune in the car for a couple of days. It worked fine. I'll put it back in once it gets hot and run it for a few weeks to be sure.

Still don't know what the 6th channel is for.
 

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6th channel is free, and good luck man.. i did the same for a couple of ECUs before and the injectors codes came in after a long idle
 
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