2007 Toyota Yaris- P2118

Got an opportunity to work on a more recent-ish vehicle ( in thread title). The owner ( close friend) attempted to solve a charging issue with the battery. he admitted to accidentally reversing the polarity when connecting the battery :ohmy: Luckily the key was OFF at the time but It blew the the high amp ALT fuse link on the battery terminal so we had to get another one fuse assembly for the + battery terminal now the the vehicle has a p2118 code for throttle position out of range/ performance.

I pop the hood to see if the connector is plugged in, and it is. So I unplug it, and key on, and it is not getting proper battery voltage, or ground via test light ( didn't have multimeter at time) . When plugged in, the throttle assembly emits a high pitched whine noise.

Checked the ETCS fuse which is needed for this circuit, all is good, then i remembered that the fuse was blown( then replaced) etc. I also noticed that ALL fuses under the hood gets power in key off.

Was researching a bit trying to find some info/ diagrams for this vehicle. I suppose my next step will be to check for power and ground for the circuit on the ecm side which is conveniently right under the hood 'gainst the firewall, and resistence to ground once I get my multimeter.

Honestly, what is the liklihood the actual ECM could have been damaged?

Well, at least your friend was honest about the reverse jump! Some customers will refuse to admit a jumping mistake, believing that it'll somehow make the repair cheaper :dry:

Anyway, good move checking the ETCS fuse, that's the first think I was going to suggest. Any chance that more fuses are blown? If it wasn't you that replaced the popped fuses, then it may be worth rechecking the fuses are in the right locations.

Honestly, what is the liklihood the actual ECM could have been damaged?

Always possible. But I've seen Toyota products get reverse jumped before, and survived.

Before going a lot deeper, I might be tempted to try a soft reset. We know that the battery went low a some point (hence the jump), and modules hate low voltage, so I say hit the reset button. Can't be any worse for the PCM than the reverse jump

For my info, does this start and run with a forced idle? Trying to rectify you finding no power/ground at the throttle body, but the throttle is making noises like it's at max travel.

Tyler wrote: Well, at least your friend was honest about the reverse jump! Some customers will refuse to admit a jumping mistake, believing that it'll somehow make the repair cheaper :dry:

Anyway, good move checking the ETCS fuse, that's the first think I was going to suggest. Any chance that more fuses are blown? If it wasn't you that replaced the popped fuses, then it may be worth rechecking the fuses are in the right locations.

Honestly, what is the liklihood the actual ECM could have been damaged?

Always possible. But I've seen Toyota products get reverse jumped before, and survived.

Before going a lot deeper, I might be tempted to try a soft reset. We know that the battery went low a some point (hence the jump), and modules hate low voltage, so I say hit the reset button. Can't be any worse for the PCM than the reverse jump

For my info, does this start and run with a forced idle? Trying to rectify you finding no power/ground at the throttle body, but the throttle is making noises like it's at max travel.

Three fuses were blown, one throttle function, another related to the starting system and one more I don't remember.

Its running rough like its in limp mode, occasionally sputtering but runs. Heres a snot of some values of freeze frame data with the connector plugged in




This is with my foot off the pedal.. Also, the battery is brand new as the old one ( oldie couldn't hold a charge due to age and usage)

Looking at the circuit I came to a realization I may not have used the test light correctly. Guess i'd need the dtc is set when the computer senses little to no power feed on the +BM wire at the ecm. So I will start there OR a soft reset- meaning to clear the code and see if it comes back?

I remembered also this is drive by wire system and cant be tested the same way as a Throttle with linkage




EDIT:

That's where I was going to suggest going if the soft reset doesn't work - tracing out the ETCS fuse circuit to the PCM and make sure it's good there. Thinking about burned fuse box connections, mostly.

And by soft reset, I meant disconnecting the battery cables from the the battery and shorting them together. Key off, of course. This serves to discharge any keep alive memory and 'reset' any modules bothered by the weak battery. I should probably mention that, if this works, then you'll need to clean the throttle body. This soft reset will also clear the PCM's throttle adaptations, and it won't relearn correctly with a dirty throttle.