Error code c1203?

Here is freeze data.
Thank you!

Yep, this is the problem.

The C1203 error code indicates a "Engine Control System Communication Circuit Malfunction."

Communication issues between the Engine Control Module (ECM) and the ABS/Traction

I would recheck the ABS fuses and I would swap out the ABS motor relay and the ABS sol relay. Here are the ABS wiring diagrams so you can see which fuses to check and a guide to help check for power and see how the system works.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Chances are the VSC ECU has gone out, but we need to make sure the power and grounds are good. Check out the images (below). Please let us know what happens.

Hello Ken,

I already checked and, just in case, replaced ABS fuses and ABS motor relay and the ABS sol relay at the beginning of troubleshooting. I even pull/split fuse box from under hood and check for oxidizes on wires/sockets. Also, check all grounds and power on ECU and SKID. However, I don't remember readings for power. Probably it is good idea to check it again.
Also, planning to check steering wheel angle sensor.
Will get back with results after weekend.
Thank you!

Sounds good, please let me know I am interested.

Good day, Ken,
I re-check power and grounds on ECT ECU and SKID – all seems OK.
I setup Techstream in hope it will somehow help - more easy to look for information and proceed with zero ground reset.

When I check all readings on ECT ECU and then on SKID, I found that RPM’s on ECT ECU is stable and equal to tachometer readings, but readings of RPM’s on SKID is all the time jumping from 0 to 1400.
I check wires from VSS to ECT ECU and SKID all show stable readings around 1.2-1.3Ohms, no shorts to ground or each other.
Also, I bought cheap oscilloscope and check readings from VSS on ECT ECU side.
TSS – NT+ show nice sinusoid; NT- show spiked sinusoid with garbage signals.
CGSS – NC+ show crazy sinusoid, with spikes, garbage signals and voltage jumping up and down.
I swap VSS, CGSS signals get less garbage signals but still have spikes and voltage jumping.
Unfortunately, I did not make a pics for it.

Then I begin check communication between ECT ECU and SKID, and during this test tachometer needle begin jumping, but VSC error did not show up at least 20 minutes, once I remove “probe” it throw VSC within 1 min.

1- ECT ECU readings before start
2- same
3 – ECT ECU after start
4- SKID before start, error already registered but not throw VSC on dash
5 – SKID after start, ECT ECU show around 760 RPM, on SKID – 319 RPM
6 - SKID after start, ECT ECU show around 760 RPM, on SKID – 0 RPM
I believe tachometer needle begin jumping when I read this pin – E8-14 (ENG+)
Readings on oscilloscope on TRC+, TRC-, ENG+, ENG- - I already confused which one which, I believe I write down in correct order as pics taken.

Since on different parts even of the same manual connectors shown under different labels, I had to mark it in same way.

I feel this issue related to different readings of RPM’s on ECT ECU and SKID.
Unfortunately, next weekend I will be busy on project, and will not be able to proceed with any troubleshooting.

It is not allow me to add pics here, will add in next thread

Add pics

Yep, these reading look okay except for the VSC ECU. If the power, grounds and connections are good I would try a rebuilt VSC ECU.

Thank you for pin-pointing to area.
Since I already replaced VSC ECU, and had same issue, I will more thorough check connectors and signals on VSC ECU board.
This weekend will not be able to work on it, will report once proceed.
Thank you very much for your help!

You are welcome, have a great weekend end and let me know ;)

Good morning, Ken,

I had not many time to work on this vehicle this weekend.
However, I re-check all power and grounds, all seems okay.

I unplug A22 connector from SKID - the one which holds communication wires from ECT ECU.
Start the vehicle and check signals (oscilloscope) with unplugged connector on communication wires: ENG+/- seems have same signal pattern, and TRC+/- seems have same signal pattern.
I know how is looking CAN-bus communication (mirroring signals) on oscilloscope, but here is different, +/- show same pattern.
NEO show something weird - completely random signals.
Is it suppose to be like that with unplugged connector? I thought TRC+/- and NEO is signals from ECT ECU and expected signals from it, but TRC+/- should be signals from SKID, which is unplugged.
Also, do you know what is NEO signal?
Had no time to check Steering Angle Sensor, but begin suspect root might be there, since everything else has been checked/replaced.

Thank you.

Hello, after many different tries, I did unpin 5 cables between SKID and ECT ECU for testing. Now it is clear that issue somewhere else, since there is no communication between units.
Vehicle, until get completely warm up, working perfectly, once warm up, begin shake (feels like gear on/off) when switch gears from 1-2 and from 2-3, more driving - more shakes, until 3 times and power slightly get cut.
Next try - replace TPS, when Ohm testing, it is weird acting, on one spot at beginning loose connection, and when touch center piece it jump readings up to 100Ohm.