Codes p1779, P1791, P0222 and P1780, lost communication with ECU

2002 SATURN L300

137 MILES

HILLROBY23

MEMBER
2 POSTS

I have checked all grounds and replaced the throttle body. I have been all over this car but it has lost connection with TCM and ECU and has throttle pedal circuit high codes. any advice would be greatly appreciated. The car will start if I unplug the throttle body and diagnostic port doesn't connect to scanner without the throttle body unplugged with it plugged in the car will start with a very light throttle response barely any.

Jan 25, 2022 at 8:16 AM

KASEKENNY

✓Experienced Mechanic
18,907 POSTS

Okay. We could have a couple other issues that we need cross off the list, but I suspect we have an issue with the ECM supplying the incorrect 5-volt reference signal.

Basically, we need to start with checking the voltage on these circuits but let's follow these specific steps so that we don't get lost.

However, here is a guide that will help with this test in case you need it:

https://www.2carpros.com/articles/how-to-check-wiring

Let me know what questions you have but the wiring diagram is included as well.

Thanks

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Jan 26, 2022 at 6:42 AM