Hey guy's I just installed Nitrous on my 2001 coupe. Tuning and all went well. Decided to test last night at the track. All was well until I shut the traction control off. Bells whistles reduced engine power and codes.

10PCM P1221 HC which is the TP Sensor. The wire that we tapped into for the window switch is connected to this. That blue wire is something like a .020 or .022 gauge and I found the we had broken it. No problem I'll just re-splice it, no good.

Also code
28-TCS C1278 HC Code list says TCS temporarily inhibited by PCM. I ASSume this is caused by the above.

I spliced into the TP sensor wire again this morning, basically to extend it. I used a .018 since the original wire is so fragile. Disconnected the battery for a hour and a half. Fired her up hit the throttle and immediately get reduced engine power and the 2 codes above AGAIN. I can clear the 10PCM code but NOT the 28-TCS code. When clearing that code it immediately comes back AND brings the 10PCM code with it.

Did I fry the Throttle Position Sensor? Is the new wire I spliced in causing the TPS to read wrong voltage due to different gauge wire?

Is the Traction Control system the problem?
Does one have anything to due with the other?
Any thoughts, suggestions, experience with this?

Thanks for your help.
Bob

 

I got the semi answer. Disconnected the MSD box and the problem is gone. Now I just need to find out if the failure is the MSD box or one of the wires from it.

 

OK still getting the 28TCS C1278 HC There is no way to clear this. Also, no code but on the bottom of the DIC Active Handling AND Traction Control Any thoughts?

I now have full throttle, just cannot disable traction control as I can't clear the TCS code.

 

You don't need to shut it off since it is already off. The PCM can't perform its part of the Traction Control function. Here is the explanation of the code you are getting:

DTC C1278
Circuit Description
The EBCM and the PCM simultaneously control the traction control. The PCM reduces the amount of torque supplied to the drive wheels by retarding spark timing and selectively turning off fuel injectors. The EBCM actively applies the brakes to the front wheels in order to reduce torque.

The EBCM sends a requested torque message via a pulse width modulated (PWM) signal to the PCM. The duty cycle of the signal is used to determine how much engine torque the EBCM is requesting the PCM to deliver. Normal values are between 10 and 90 percent duty cycle. The signal should be at 90 percent when traction control is not active and at lower values during traction control activations. The PCM supplies a pull up voltage of 5 volts that the EBCM switches to ground to create the signal.

The PCM sends a delivered torque message via a pulse width modulated (PWM) signal to the EBCM. The duty cycle of the signal is used to determine how much engine torque the PCM is delivering. Normal values are between 10 and 90 percent duty cycle. The signal should be at low values (around 10 percent) at idle and higher values under driving conditions. The EBCM supplies a pull up voltage of 12 volts that the PCM switches to ground to create the signal.

When certain PCM DTCs are set, the PCM will not be able to perform the torque reduction portion of traction control. A serial data message is sent to the EBCM indicating that traction control is not allowed.

Conditions for Setting the DTC
The PCM diagnoses a condition preventing the engine control portion of the traction control function and sends a serial data message to the EBCM indicating that torque reduction is not allowed. The PCM will typically set a DTC and the EBCM will set this DTC.

Action Taken When the DTC Sets
If equipped, the following actions occur:

The EBCM disables the TCS/VSES for the duration of the ignition cycle.
The Traction Control and Active Handling indicator turns ON.
The DIC displays the following messages:
Service Traction System
Service Active Handling
The ABS remains functional.

Sounds like you need to do some more work getting the wiring sorted out.

Bill

 

Thanks for the info Bill.
2 questions, is it possible that since I used a different gauge splice for the TPS wire, that the voltage being read by the PCM is now wrong? Or does the TPS wire have nothing to do with this?


Thanks
Bob

 

Not sure how you performed the splice and not sure a different gauge wire would cause that much of a problem.

But depending on how you wired the nitrous circuit into the TPS circuit the balance of the TPS circuit could have been changed. This is how the TPS circuit works:

DTC P1221
Circuit Description
The throttle position (TP) sensor is mounted on the throttle body assembly. The sensor is actually 2 individual TP sensors within 1 housing. Two separate signal, low reference and 5 volt reference circuits are used in order to connect the TP sensor assembly to the throttle actuator control (TAC) module. The 2 sensors have opposite functionality. The TP sensor 1 signal voltage is pulled up to the reference voltage as the throttle opens, from below 1 volt at closed throttle to above 3.5 volts at wide open throttle (WOT). The TP sensor 2 signal voltage is pulled down to the low reference from around 3.8 volts at closed throttle to below 1 volt at WOT. TP sensor 1 and APP sensor 1 share a 5-volt reference circuit that is connected within the TAC module. TP sensor 2 and APP sensor 2 share a 5-volt reference circuit that is connected within the TAC module. If an out of range condition is detected with the TP sensors, this DTC will set and the Reduced Engine Power message will be displayed.

Conditions for Running the DTC
DTCs P1517, or P1518 are not set.
The ignition switch is in the crank or run position.
The ignition voltage is greater than 5.23 volts.
Conditions for Setting the DTC
TP sensor 2 disagrees with TP sensor 1 by more than 7.5 percent.
All above conditions are present for less than 1 second.
Action Taken When the DTC Sets
The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame and/or the Failure Records.
The control module commands the TAC system to operate in the Reduced Engine Power mode.
A message center or an indicator displays Reduced Engine Power.
Under certain conditions the control module commands the engine OFF.

In your first post you say you wired the window switch into the TPS sensor blue wire. This is circuit 417 and it provides the throttle position feedback signal to the TAC. If you loaded (reduced the voltage level) this signal by splitting the current with the window switch then you have unbalanced the overall circuit as the voltage of 417 is compared to circuit 427.

Bill

 

Very interesting Thank You