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[Jeremy556]

You are good at this. You should move out here to western Colorado; best trails in the country all around, 2 Toyota dealerships in 500 miles and only 1 or two (worthless) Toyota Techs between them, with a minimum of 6 weeks to get an appointment, when they're slow.

Example:
I waited months after installing my Toyota VIP remote start system to get into the dealer to perform the 2 minute, flash of the immobilizer to recognize the remote start. Was charged for several hours labor and told my system was bad. I stressed repeatedly to the service writer, and made my way into the service bays and told the "tech" to make sure to short the 1P RES connector in the passenger foot well (even left the panel off for them).

Eventually I found a local indy shop (Safari LTD, can't recommend them enough) that has a Mongoose cable, asked them to perform the same procedure while doing an alignment. They actually had to remove the passenger kick panel, but had no problem registering the remote start.

 

[JLee50]

As this was one of the threads I found when I was troubleshooting a nearly identical issue, I'll drop this here in case it helps anyone else.

I have a 2005 Lexus GX470 and had the below codes (identical to the OP's except I didn't need a ZPC):

C1203- Engine Control System Communication Circuit [Current DTC]
C1340- Open Center Differential Lock Signal Circuit (During Center Differential Lock On) [Current DTC]

I also experienced the CDL light flickering for a few months (CDL wouldn't engage) and then it stopped flickering and went solid out. I eventually decided that I needed a new skid control ECU, so I bought a master cylinder assembly on eBay and swapped it out. I immediately lost the C1203 code and just had C1340 remaining. The CDL still would not engage (keep in mind the GX is full time 4wd with an electronic CDL). Further investigation showed that the 4wd control ECU (screwed to the plastic panel underneath the glove box) was not completely plugged in. I reseated the plug and all is now well with the world. My full thread is here for reference.

 

[doublezero]

vacume issue

There is some kind of vacuum issue.

I would go for the easy stuff 1st like feeling the gas cap for tightness.

Then I would unplug and replug all the vacuum hoses in the engine and run it around the block twice with a shutdown and restart.

 

[frankthetank820]

C1203 Code

First time posting here so sorry if I'm in the wrong location as I know this is an old post and I cannot create a new post.

My 2006 V6 4Runner is throwing a C1203 code (only code in system), so I took the vehicle to the dealership and they said it was a bad ECM. Instead of paying over $1000 for them to install a new one, I went online and bought a used ECM that I replaced myself and took to the dealership to re-program. After completing the re-program, the C1203 code remained in the system even though the guy said the replaced ECM was working properly(at least enough to get the vehicle to start and drive properly). Now they want me to take the vehicle back in for further diagnosis and spend $130 an hour on something I've already thrown alot of money at. Any chance that anybody knows a solution? I tried clearing the code, disconnecting battery for several hours etc.. but nothing has worked. Just wanted to know if I need to buy a new skid ECU as well. THANKS!

 

[Greydog]

First time posting here so sorry if I'm in the wrong location as I know this is an old post and I cannot create a new post.

My 2006 V6 4Runner is throwing a C1203 code (only code in system), so I took the vehicle to the dealership and they said it was a bad ECM. Instead of paying over $1000 for them to install a new one, I went online and bought a used ECM that I replaced myself and took to the dealership to re-program. After completing the re-program, the C1203 code remained in the system even though the guy said the replaced ECM was working properly(at least enough to get the vehicle to start and drive properly). Now they want me to take the vehicle back in for further diagnosis and spend $130 an hour on something I've already thrown alot of money at. Any chance that anybody knows a solution? I tried clearing the code, disconnecting battery for several hours etc.. but nothing has worked. Just wanted to know if I need to buy a new skid ECU as well. THANKS!

Have you seen this?https://www.toyota-4runner.org/attachments/problems-warranty-issues/14994d1197276901-one-cause-fix-vsc-trac-vsc-off-lights-zero-point-calibration-br005-03_vsc-light-dtc-c1203.pdf

 

[frankthetank820]

Have you seen this?https://www.toyota-4runner.org/attachments/problems-warranty-issues/14994d1197276901-one-cause-fix-vsc-trac-vsc-off-lights-zero-point-calibration-br005-03_vsc-light-dtc-c1203.pdf

Yes, I had looked into that and I believe that was an issue with the 2003 4runner that was fixed by Toyota on newer models.