ABS, Brake, Amber Triangle, Traction, Parking all lights on

My Prius 2010 cold start engine rattle was there for sometime without check engine light. Sometime misfire on cylinder 1 (P0301) would come on and be gone itself. Later on going and staying over 60mph for sometime when engine is properly heated would make it rattle. The coolant level was found low and replenished but the symptoms still carried on the same way till one morning the car was all white smoke from the tail pipe i.e. an indication of a shot heat gasket. At that time I replaced the head gasket myself in my garage.


At the time of head gasket replacement there were no DTCs or check engine light for any reason. After carefully replacing the head gasket the car started with similar engine rattle. 12Volts battery replacement and MAF sensor cleaning took care of the rattle. The car now starts fine without rattle but it now shows ABS, Break, Amber Triangle, Traction and Parking Lights on. Beep and a message "shift to P" starts to flash on the dash board. There is still no check engine light but ABS system DTCs are there which are C1203, C1345 and C1392(sometime). It looked very much like communication problem between the ECU and EV or ABS system as if some connector was not reconnected after head gasket work but I've verified it multiple times already. Everything looks ok.


There are no direct sensor codes that turn on the check engine whether it be wheel speed sensors like C1464 or any other sensor or actuator that I might have damaged or left disconnected after head gasket work. That is why I tend to believe it is some sort of communication problem. Techstream also shows C0371 i.e. the yaw rate sensor which is located underneath and hand rest and I never touched that area. My Innova shows roughly 16 enhanced OEM DTCs but again there is no check engine light and the main codes scanner shows are ABS related i.e. C1203 and C1345. Any help is appreciated.

 

I wonder how would it happen all of a sudden i.e. prior to head gasket replacement it was working fine without ever showing any electrical malfunction and now after head gasket replacement I see this ABS/Traction related DTCs. Can any measurement or a simple method reveal the the problem or do I have to dismantle stuff to work on the ECU/EV/ABS.

 

None of that because there wasn't any problem with either the brake or ABS... Just the head gasket replacement.

 

I have gone through the "Utility" menu under ABS/VSC/TRAC section in Techstream and have done linear solenoid valve offset and other calibrations couple of times too but nothing helped so far. Couple of things that I noticed during the linear valve cal 1. The procedure mentions that the lights be flashing/blinking during the cal but mine never does although it completes the 120 sec calibration every time but to doesn't change anything (which to me means cal not done properly) and secondly sometimes I receive message saying "lost communication with the vehicle..." but then redoing it works fine. I guess the lost communication is related to my J2534 interface. Can you please share the manual's procedure for these calibrations here. It may be that I am missing some crucial step(s) in the manual's procedure.

Among the 16 enhanced OEM codes some could be related to timing so opened up the valve cover and verified that the timing chain yellow/amber marks were set right and harmonic balancer also showed 0 deg and everything does look perfect. The codes are P0171, C3200, P0101, P1E03, P0012, P3700, P0201, P0125, P2801, P0137, P3801, P0141, P0104, P0420, P3E04 and P0441.

 

These codes were read by my handheld innova 3150 scanner. I know some of these codes are non-existent or not defined. Remember these are enhanced OEM codes. May be these Toyota/OEM specific codes are not recognize by Innova and spits gibberish for the code. For whatever reason my dash lights don't blink no matter what I do during the cal procedure. I think I did clear the memory in my last attempt too.

The mind boggling thing for me is that all the systems were perfectly working before head gasket replacement and I never touched the ABS or braking system or the yaw rate sensor during head gasket replacement and getting these codes all of a sudden after head gasket replacement just makes it a big puzzle.

We love these Priuses and so my wife also has a 2012 Prius. This evening I am going to run these scans and cals on her Prius and see what do I get using my Techstream on her running Prius.

 

I scanned my wife's Prius for ABS statuses and found some differences than mine. The important ones are the red highlighted items here in the pictures.

I ran the linear valve offset calibration on her car and it worked fine with blinking ABS/VSC/TRAC lights. My car ABS/VSC/TRAC lights stay solid during the calibration even after doing memory reset. I think the red highlighted status differences and calibration issues are all related to ECU communication (code P1203).

The Enhanced OEM codes have changed couple of times in the last few days. They were completely gone one time too. From yesterday to now these codes have changed again. Now there are 12 codes left instead of 16 and they are P1203, P0171, C3201, P0103, P2501, P0136, P3701, P0139, P0104, P0420, P1521, P2610.

 

I think the linear valve offset is not functional which to me relates to communication error C1203. If someone has the manual that shows the wiring diagram and diagnostic steps for C1203 that will help.

Chapman can you please review ABS Brake Problem: Error Codes C1203 and C1345 | PriusChat and let me know if replacing the ABS actuator as a first step "in the air" makes some sense. In the air because there's still no clear diagnostics so far that points to actuator itself being the problem although the codes could be related to the actuator.

 

C1203 TOYOTA ECM Communication Circuit Malfunction (autocodes.com) says that the C1203 TOYOTA Possible Causes are 1. Faulty Engine Control Module (ECM) 2. Engine Control Module harness is open or shorted 3. Engine Control Module circuit poor electrical connection

Is this not over simplistic? Could a non-responsive ABS actuator not pop this code?

 

I am clueless right now because I don't

Yes I noticed that smokeGTI's case may not be apple vs apple although very similar but I still welcome him to the club

The part of harness I interacted with during head gasket replacement had nothing to do with ABS, speed sensors or braking in general, I strongly believe that harness or connectors is not likely to be the issue. Even if that was the case I would expect a direct sensor code (like speed sensor) which is not the case. I still went ahead and inspected the harness and cleaned the connectors which were as clean as new already.

I am completely out of luck, out of options now and so I have decided to take a "logical guess" based stab at it. I am going to replace the ABS actuator first with a used functional one and see where does it lead me to.