The engine control module in my 2008 dodge sprinter is not putting out a 5vdc signal to the fly by wire accellarator pedal so the engine won't start. The mechanic disconnected all the sensors one by one and engine still would not start or even start and go into limp mode. They say its the ecm but they sound unsure? Is there a hidden fuse on the 5vdc somewhere? I've tried both my keys in case the engine wasnt recognizing one but still no start
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Re: The engine control module in my 2008 dodge sprinter...
One way is to cut the 5v wire in a place thats easy to repair, near the computer, and see if it comes back to life. if not, it needs an ECM ...IF it does, then you still need to find out what else is connected that is shorting out your 5v ref voltage. But either way you need to find out where the short is, you dont want to wipe out a new ECM if the old one is bad.
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How did you determine it's not the turn signal arm? The arm is part of the multifunction switch, which also controls high/low beam headlights, hazard lights, and (on many vehicles) wiper/washer functions. A lot of electrons flying around there.
The other possibility is the body control module - I think it's called the totally integrated power module (TIPM) on your vehicle. You'll need a service manual to properly troubleshoot either the multifunction switch or the TIPM.
Good case study on a similar problem at the link.
2506 PCM/ECM Power input signal range/performance 110 IAT Intake Air Temp sensor 1 circuit 104 MAP/ Baro sensor low input You probably did do some damage by not isolating the engine and controls out before the repairs/mods were started.
• Powertrain Control Module Description for the 2.8L engine
• Powertrain Control Module Description for the 3.5L engine
Throttle Actuator Control (TAC) System
Throttle Actuator Control (TAC) Overview
The throttle actuator control (TAC) system uses vehicle electronics and components to calculate and control the position of the throttle blade. This eliminates the need for a mechanical cable attachment from the accelerator pedal to the throttle body. This system also performs the cruise control functions as well.
The TAC system components include, but are not limited to the following:
• The accelerator pedal position (APP) sensors
• The throttle body
• The powertrain control module (PCM)
Each of these components interface together to ensure accurate calculations and control of the throttle position.
Accelerator Pedal Position (APP) Sensor
The accelerator pedal position (APP) sensor is mounted on the accelerator pedal assembly. The APP is 2 individual APP sensors within one housing. There are 2 separate signal, low reference, and 5-volt reference circuits. APP sensor 1 voltage increases as the accelerator pedal is depressed. APP sensor 2 voltage decreases as the accelerator pedal is depressed.
Throttle Body Assembly
The throttle body for the throttle actuator control (TAC) system is similar to a conventional throttle body with several exceptions. One exception being the use of a motor to control the throttle position instead of a mechanical cable. Another exception is the throttle position (TP) sensor. The TP sensor is mounted in the throttle body assembly. The TP sensor is 2 individual TP sensors within the throttle body assembly. Two separate signals, low reference, and 5-volt reference circuits are used to connect the TP sensors and the powertrain control module (PCM). TP sensor 2 signal voltage increases as the throttle opens. TP sensor 1 signal voltage decreases as the throttle opens.
Reduced Engine Power Mode
When the PCM detects a problem with the throttle actuator control (TAC) system the PCM enters one of the following Reduced Engine Power Modes:
• Acceleration Limiting--The control module will continue to use the accelerator pedal for throttle control, however the vehicle acceleration is limited.
• Limited Throttle Mode--The control module will continue to use the accelerator pedal for throttle control, however the maximum throttle opening is limited.
• Throttle Default Mode--The control module will turn OFF the throttle actuator.
• Forced Idle Mode--The control module will perform the following actions:
- Limit engine speed to idle by positioning throttle position, or by controlling fuel and spark if throttle is turned OFF.
- Ignore accelerator pedal input.
• Engine Shutdown Mode--The control module will disable fuel and de-energize the throttle actuator.
Have you had it checked for DTC'S - diagnostic trouble codes ?
The commanded throttle position (TP) is compared to the actual TP. Both values should be within a calibrated range of each other. The powertrain control module (PCM) continuously monitors the commanded and actual TPs. If the values are greater than the calibrated range, DTC P2176 sets.
The accelerator pedal position (APP) sensors 1 and 2 are located within the accelerator pedal assembly. Each sensor has the following circuits:
• A 5-volt reference circuit
• A low reference circuit
• A signal circuit
This provides the powertrain control module (PCM) with a signal voltage proportional to accelerator pedal movement. The APP sensor 1 signal voltage at rest position is near the low reference and increases as the pedal is actuated. The APP sensor 2 signal voltage at rest position is near the 5-volt reference and decreases as the pedal is actuated.
The throttle actuator control (TAC) assembly has 2 throttle position (TP) sensors mounted within the assembly. The powertrain control module (PCM) provides individual signal, ground, and 5-volt reference circuits to each sensor. Both sensors operate within a voltage range between 0.35-4.65 volts. When the throttle is opened from 0-100 percent, one sensor signal voltage increases while the other decreases. The signal circuit for TP sensor 1 is referenced to ground, and the signal circuit for TP sensor 2 is pulled up to 5 volts within the PCM.