2006 Scion TC Misfire on #1

2006 Scion TC 2.4L 4cyl
Misfire on #1, no spark from coil, has injector pulse
Swapped coils, problem did not follow
Scoped IGT #1 cyl and found base voltage not at 0v instead it is at 2.8v and then goes to 4.3v when computer commands on.

Disconnected affected circuit (coil and pcm). Then put a light bulb on one end of the circuit and powered the other end of the circuit with my powerprobe. Bulb lights good on the IGT circuit. Checked all other circuits ok.

Attached some pico captures. Can someone lead me in the right direction. I am thinking the ECM is at fault at this time.

One more thing, when I unplug the connector from the affected cylinder. The wave form goes normal 0v-4v square wave. Plug in, back to 2.8-4.3v square wave.

I wonder if current ramp for #1 coil might show difference compared to other coils. Maybe compare amp waveform moving #1 coil to good IGT driver.

not to experienced but that turn on oscillaition doesn't look right nor does the ramp of the current looks like lazy driver

I did do that, it was pretty much the same as a known good.

I think its safe to say it needs a computer. The circuit is so simple, 1 wire for IGT straight to the coil. The coil was switched around and the problem didn't follow. Checked all 4 coil circuits, good. I'm going to order a computer, thanks guys.

Try leaving only #1 connected and see if signal returns to normal.

To the OP. Please let us know the end result and how the process went. Always good to read and learn.

eliteautosolution wrote: I think its safe to say it needs a computer. The circuit is so simple, 1 wire for IGT straight to the coil. The coil was switched around and the problem didn't follow. Checked all 4 coil circuits, good. I'm going to order a computer, thanks guys.

I agree. Please let us know when you get the computer in

FIXED

Rechecked all the wiring to the coil. The ground and IGT wire was swapped on the connector. Called customer and asked them were they fooling around with the coils, and they said they just changed the plugs. Then a long pause.............customer finally said the wiring came out when they connected the coil back up. These problems I encounter seem to always be a customer inflicted issue. But another one in the books and I know I should have caught this yesterday.

huh interesting I wonder how you got waveform like the one you did it seems like it would have come up inverted not sure though the top was missing maybe that was the ground

I don’t know how many customers do it on purpose but they all seem to leave out important details like that

eliteautosolution wrote: FIXED

The ground and IGT wire was swapped on the connector.

Nice. :silly: I was wondering about the coil ground as I was reading this thread. Well done interrogating the customer.