[houtan]

After verifying my wiring appeared to be good, I decided to purchase a pico 2204a oscilloscope to continue my diagnosis. I had never used an oscilloscope before so I watched a lot of youtube videos to learn how to use one and also what to look for.

I connected the leads to the can H and L wires under the white dme box. Once i opened the sw and saw the waveforms it was clear something was causing an issue on the PT can network. The first picture below will be a snapshot of what i was seeing.

From there i decided to start unplugging modules, and the first one i removed was my BPM4 (my aftermarket ekp). once removed I walked over to my computer screen and bingo, my PT can network signals looked normal again! Wow. i was very surprised to say the least that my robust ekp upgrade was causing the issue. PT can H and L should start at 2.5v, from there H should go up to around 4v or less, L should go towards 1.0V or less., and they should mirror each other. What was almost impossible for me to figure out with just a voltmeter is I was seeing 60ohms over the canbus wires at the BPM4, which meant it was functioning. But the oscilloscope showed me the truth! haha.

I tested the ekp a few times. sometimes it seemed to cause PT Can bus issues immediately, sometimes it took four or 5 minutes. This behavior definitely had me second guessing if it was actually the real issue. But it was the only thing that made sense (in my head at least).

Thankfully, Torqbyte, the company that created the bpm4 and sold the circuitry to EOS, was very responsive. I worked with a gentlemen named Kev, and based on my oscilloscope results, he thought it was probably the BPM4. But not 100%. So I sent the BPM4 to torqbyte so they can investigate.

Torqbytes initial check showed the resistor was working. But a few days later I received another email from Kev saying the engineers were able to find the resistor had a bad or poor solder connection that was
causing an intermittent issue! The resistor was soldered by EOS during assembly of their version of the BPM4, and it was not done correctly. Whew, boy was i relieved.

The PT can bus terminates with a 120 ohm resistor at two locations, the DSC and the EKP (or BPM4 in my case). The intermittent connection on the BPM4 side was causing all of the issues on the entire network.

The BPM4 should be back in the mail today and in my hands by the end of the week hopefully. I still have a lot of coding to add back in that I had to remove during my testing, but I am looking forward to getting my car back on the road.

Also, I realized why I was able to reflash my DSC, which I mentioned in my prior post. My guess is the BPM's intermittent connection was working for the time period it took to reflash in winkfp, and I just got lucky.

First picture is PT Can bus with BPM4 connected. Second is with it disconnected.