Error codes on road trip

[G0lden]

I’m wondering if anyone might have some ideas of what could be going on. I’m in the middle of a cross country trip pulling a ~2500# trailer when my check engine, VSC TRAC and VSC OFF lights came on. I stopped by AutoZone and read off the following codes:

P2772 - 4WD low switch circuit
C1201 - Engine control system malfunction

The truck is running great, no difference is that I can tell. I have noticed the center console getting a bit warmer than I recall, but not overly hot. I’ll admit that I’m not very mechanically inclined; that is, if I were to change my own oil I could do it, but I’d definitely need to read up on it first. Any ideas what I may be looking at? Anything I should keep in mind as I continue driving? I don’t really have an option to stop unless it were something critical. Really appreciate any thoughts here!

 

[G0lden]

Update: MAINT REQD light came on now too. I’m not sure what to make of that, seems to still be running normally.

 

[dwh13]

Update: MAINT REQD light came on now too. I’m not sure what to make of that, seems to still be running normally.

If it flashes a few times then goes off each time you start the car, it's just a reminder to change your oil. It's based purely on mileage. You can reset it following the steps in the manual if you like.

 

[G0lden]

Hmm. It stays on the whole time I’m driving, along with all those other lights. Good to know though.

 

[saucebox]

Hmm. It stays on the whole time I’m driving, along with all those other lights. Good to know though.

Can't remember if it's supposed to be on the regular ODO or on Trip A, but if you hold the button down that switches between the two, then turn the key to 'ON', it'll go away after a few seconds. Just hold the button down until the maintenance light flashes a few times, then it will go out.

 

[G0lden]

Thanks, I’ll give that a try. Any thoughts about the other codes it’s throwing?

 

[saucebox]

P2772—maybe just a sensor malfunction? It's the circuit that determines if you are in low gear in the transfer case. If everything is running normally, I'd probably leave it until you get back from the trip (but seriously monitor everything, especially temp as you go along).

C1201 seems a little more...difficult. The only thing I found was a manual for an FJ Cruiser, and its diagnosis was to just replace the engine control system. Sounds expensive.

By any chance, is yours an '06 or '07? C1201 might refer to the air injection system and a malfunction there. Searching on that here might net better advice. I don't have any experience with air injection.

 

[G0lden]

It's a 2005 LX. Interesting. Once I found out what the codes were I was pretty concerned. The lights were on for a couple days and roughly 700 miles of driving. As of yesterday they cleared and only the MAINT REQD light was on, likely for the oil change as previously mentioned. I'm wondering if the towing and warm outside temps caused a sensor somewhere in the transmission/transfer to malfunction like you said, which resolved once it sat for a couple days. I'll be keeping a close eye on it!

 

[Petertn45]

I’m wondering if anyone might have some ideas of what could be going on. I’m in the middle of a cross country trip pulling a ~2500# trailer when my check engine, VSC TRAC and VSC OFF lights came on. I stopped by AutoZone and read off the following codes:

P2772 - 4WD low switch circuit
C1201 - Engine control system malfunction

The truck is running great, no difference is that I can tell. I have noticed the center console getting a bit warmer than I recall, but not overly hot. I’ll admit that I’m not very mechanically inclined; that is, if I were to change my own oil I could do it, but I’d definitely need to read up on it first. Any ideas what I may be looking at? Anything I should keep in mind as I continue driving? I don’t really have an option to stop unless it were something critical. Really appreciate any thoughts here!

Hello,

Any update on a fix or solution on the P2772 code "4WD low switch circuit range/performance"?

My 2006 LX 148k miles is throwing this code after a CEL, VSC TRAC, VSC OFF lights came on. Cleared it couple times and comes back. This happened after my battery decharged after not driving for a few days and had to put it on charger. Drove around normal streets first, and then all these lights came on (also had ABS light come on but went off) while driving on the highway around 70mph. I've placed it into 4low and back into hi w/o trouble. Now driving around city streets, the RPM's go up to about 2300 around 50mph and doesn't seem to shift up to next gear.

Battery and alternator check out okay at AutoZone. Battery is new from Lexus 4/2019.

Recent work done 1 week before:
-PCV valve and 2 hoses
-Serpentine belt
-Installed a Tekonsha P3 brake controller by connecting under dash with tacoma harness (plug n play) and removed middle console but rechecked all wiring

Thanks for any help in advance,
Peter

 

[jerryb]

5th gear probably isn't available. I think i'd shift a bunch from 4 lo to hi and see what happens.
then I might unplug the switch at the transfer case and see what happens, and check the codes again.
then I might take out the switch and push the ball at the end of it.
check the transfer section of the online 04 manual.
it's about the same as the 2006.
disclaimer is that I've never touched one and I haven't looked to see where it is. Probably right by the neutral switch I would imagine.

 

[Petertn45]

5th gear probably isn't available. I think i'd shift a bunch from 4 lo to hi and see what happens.
then I might unplug the switch at the transfer case and see what happens, and check the codes again.
then I might take out the switch and push the ball at the end of it.
check the transfer section of the online 04 manual.
it's about the same as the 2006.
disclaimer is that I've never touched one and I haven't looked to see where it is. Probably right by the neutral switch I would imagine.

Went out today and again went through the online manual Transfer section. My CDL switch functions fine, but the CDL light didn’t turn on when I moved from 4H to 4L (manual says check this). Anyways, moved it back and forth several times, and the dash lights and code haven’t come back after driving it around. Luckily didn’t have to disconnect the switches etc. Also it did rain very hard recently so wonder if some water got into a harness.

Thanks for the help and will update thread if the problem returns.

 

[Pick]

My wife called and said she bumped the CDL button and it wouldn't turn back off. After pulling up and back a few times in the parking lot, it finally went out. She called me back in a few minutes and said the CEL & VSC lights were on. When she got home I read the codes and got a P2772 "Four Wheel Drive (4WD) Low Switch Circuit Range/Performance" code. I cleared it and it went out and didn't come back on. This weekend, I thought I'd exercise the transfer case and CDL since I haven't used it since buying it back in March. It cycled through L & H with the CDL on and off with no problem ...but as I got on the road to come back home, the CEL/VSC lights came on. Read the code when I got home and got the same thing. I haven't found anything definitive on MUD (or anywhere else for that matter). For now, clearing the codes afterwards seems to work but I'll continue to troubleshoot it.

It was raining VERY hard (TS Eta) when this happened the first time so not sure if that is just coincidence with @Petertn45 's experience or not???

If you've seen this resolved before - would love to pick your brain... Thanks!!