Okay,the story....got a '98(NO active handling)coupe and SVS shows up every time I start the car and drive it,even for a couple of yards.After reading the codes,the C1281 code keeps popping up and checked al these things:wiring,connectors,ground connectors and even the SWPS.That thing gives 2,5V when the steering wheel is in a straight position and when steering to the left and right it fluctuates between 0.25V(most left position)to 4,9V(most right position).What else can I do to find the culprit who sets this code C1281??
Any suggestions would be much appreciated...
Does anyone know where to find the "yaw rate and lateral rate sensor"??

Greetz Erik.

 

Is the C1281 the ONLY DTC being set, or are you getting something like a C1287 also ???

 

No other codes what so ever....just the C1281.Cleaned all grounds and connectors.After resetting the C1281 code,starting the car up,back and forth a few times and the C1281 code kicks in...

Greetz Erik.

 

Just to make sure, you are getting a Service Vehicle Soon message and not an SES indicator??? C1281 will generate a Service Vehicle Soon message but not a Service Engine Soon message.

Your analog voltage measurements look OK but the problem could be with the digital values. The code is set when there are differences between the analog and digital values so you may need access to a Tech 2 to determine if the digital side is working or something else has gone amiss with the Phase A (pin 3), Phase B (pin 4) or Index Pulse (pin 5) signals. If the EBTCM isn't pulling them up the problem could be in the EBTCM. You could check each of those points at the SWPS connector and see if you get a 12V reading when the ignition is on.

Here is the Theory of Op for the SWPS/EBTCM and what conditions set the code:
DTC C1281 Steering Sensor Uncorrelated Malfunction Without RPO JL4

Circuit Description
The EBTCM uses four inputs from the Steering Wheel Position sensor:

Phase A digital input
Phase B digital input
Index pulse
Analog input
This information is used to calculate three things:

The front wheels position when centered.
The front wheels position when turning.
The vehicles lateral acceleration.
The EBTCM runs a centering routine when the vehicle speed goes above 30 Km/h (18 mph). When the vehicle reaches 30 Km/h (18 mph), the EBTCM monitors the Steering Wheel Position Sensor inputs (Phase A, Phase B and Analog voltage) to see if the steering wheel is moving. If the steering wheel is not moving for a set period of time then the EBTCM assumes the vehicle is going in a straight line. At this point, the EBTCM looks at the analog voltage signal and reads the voltage. This voltage normally around 2.5V, is then considered the center position and the digital degrees also become zero at the same time. This centering routine is necessary to compensate for wear in the steering and suspension. Wear in the steering and suspension can result in a change in the relationship between the steering wheel and the front wheels. By running the centering routine the EBTCM can compensate for these changes by changing the digital and analog center position.

The EBTCM uses the digital input (Phase A and Phase B) from the Steering Wheel Position Sensor to calculate the direction the driver of the vehicle is trying to steer during an ABS event. This information is also used to calculate the vehicles lateral acceleration for Magnasteer®2.

Conditions for Setting the DTC
DTC C1281 will set when the digitally derived centered angle differs from the analog derived angle by 27 degrees or more for a period of 5 seconds.
DTC C1281 will set if the index pulse is not seen between ± 37 degrees or is seen between -185 degrees and -37 degrees or 37 degrees and 185 degrees of steering wheel travel.
DTC C1281 will set if phase A and or phase B are shorted.

Action Taken When the DTC Sets
Magnasteer®2 is disabled, ABS/TCS remains active.

Messages displayed on the DIC:

Service Vehicle Soon

Conditions for Clearing the DTC
Condition for DTC is no longer present and scan tool clear DTC function is used.
Fifty ignition cycles have passed with no DTCs detected.
Diagnostic Aids
If the analog Steering Wheel Position Sensor input is missing then DTC C1288 will set.
If the Steering Wheel Position Sensor 5 volt supply or the Steering Wheel Position ground is missing DTC C1288 will set.
It is very important that a thorough inspection of the wiring and connectors be performed. Failure to carefully and fully inspect wiring and connectors may result in misdiagnosis, causing part replacement with reappearance of the malfunction.
An intermittent malfunction can be caused by poor connections, broken insulation, or a wire that is broken inside the insulation.
If an intermittent malfunction exists refer to Testing for Electrical Intermittents in Wiring Systems.

 

Hi Bill,first of all....yes it's a service vehicle soon message :o
All the wires we measured had the values you say they must have!!
So the digital and analog values are good I guess.What's the story about the yaw rate and lateral rate sensors...can they be a part in this story?
What if one of these things were broken??We kind of know now how the system works but still can't figure out(with all of these good analog and digital values)why it still sets this code.Unfortunatelly we do not have a TECH 2 tool....but still,all help is welcome
Ooohh btw,there is also a connector "clipped" on the front cradle and it leads a wire into the steering-housing(sorry,can't find a word for that..)Where is this wire for?(VES maybe?)

Greetz Erik.

 

You do not have a Lateral Acceleration Sensor in your car. Only Active Handling cars have that sensor. Lateral acceleration in a non-AH car is determined by calculating it from the steering sensor inputs.

As for the voltages it is good that you have 12 V coming from the EBTCM to pull up the SWPS digital lines but that doesn't mean digital signals are present or are can be oriented correctly to the analog signal which is the reference for straight ahead.

Has the steering shaft been disconnected from the steering rack recently? If so this could be the problem if it was disconnected without the shaft being mechanically locked into place under the hood. Without locking into place the shaft can be turned and the SWPS can be out of synch with the steering or it can be damaged.

It is difficult to know for sure without seeing it and tracing the wires but the connector on the front with wires going into the steering rack (gear) maybe C107 which is a 2 cavity connector with one ground wire and the magnasteer control signal.

Pin----Wire Color---Circuit No.----Function
A------GRY---------1787---------MAGNASTEER® Actuator Control
B------WHT---------345----------Ground

Bill

 

Bill,steeringshaft has never been connected.The code just showed up one time driving the car.It's been there ever since.We are still looking for damaged wires/connectors as we speak.

Greetz Erik.

 

BUMP!

I have what might be the same problem and was curious how you fixed it before I clean every damn wire in my plastic car.

Thanks!

 

Recently replaced ebcm with a used one( only one available) because it said no communication..It fixed that problem but then kept getting service abs and the codes C1225 and C1281. Cleaned grounds i could find and took off left front wheel and cleaned sensor wire..Now all Im getting is the C1281 code. Is there a simple fix for this or am i doomed to find someone to work on it.

 

bump

 

I got the C1281 tonight after taking a hard right turn over some broken pavement.

No other codes set.

Resetting it through the DIC does not re-enable the disabled systems?

 

Is this voltage reading read with the meter across the two wire sensor in the rack? I'm getting this 1281 code only and have just had the harmonic balancer replaced. Shop said the steering wheel would be off if the relationship between the rack and the column has been changed, and it is not, so ruling out that this is the cause. Measured across this sensor and it is 3.8V and does not change when the wheels are turned. Thanks

 

bookmarked... this sounds similar to my issues.

 

I trying to get my hands on a manual, so I can get my self educated enough to post here........