Where can I find a free ecm pinout diagram for a 2004 dodge neon?

The overheated wires smell is worrying and the ECM is in that location . You probably have burnt connector pins or a damaged board. That could cause the 5 volt reference issues. You need an auto electrician.

https://www.google.com/search?q=2008+Dodge+Sprinter+ECM+location

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Do you know anything about ECM five volt reference circuit's ?
DTC P0641: 5-Volt Reference 1 Circuit
The engine control module (ECM) has 3 internal 5-volt reference busses called 5-volt reference 1, 5-volt reference 2, and 5-volt reference 3. Each reference bus provides 5-volt reference circuits for more than one sensor. Therefore, a fault condition on one 5-volt reference circuit will affect the other 5-volt reference circuits connected to that reference bus. The ECM monitors the voltage on the 5-volt reference busses.

The 5-volt reference 1 bus provides 5 volts to the following sensors:
• The manifold absolute pressure (MAP) sensor
• The clutch apply sensor
• The fuel rail sensor
• The fuel tank pressure (FTP) sensor
• The intake air pressure and temperature sensor

You have a shorted sensor more then likely or wiring problem . Suggest you watch this video .
How to check the 5v reference circuit for short to ground Cadillac

code p 1598 is a/c pressure sensor--volts to high
code p0123 refers to throttle position(TP) sensor A/ accelerator pedal position (APP) sensor A---high input===causes wiring short to positive--TP/APP sensor---ECM
it also refers to TP sensor A APP switch A--low input====causes --wiring short to ground--Tp/APP switch---ECM

code p 0688 refers to engine control relay---short to positive===causes ---wiring short to positive--engine control relay---ECM
it also refers to ECM power relay control---circuit open===causes --wiring---ECM relay

First you have test the circuit to find out if it's shorted or an open circuit ! Do you have DVOM - digital volt ohm meter ? You can buy a cheap one for $10.00 - 15.00 at auto parts store . Then you'll need wiring diagrams so you test the right circuits . You can find free wiring diagrams at http://bbbind.com/free_tsb.html . You mite want to watch this video .https://youtu.be/efKoWifdcag

Possible causes
- Faulty Engine Control Module (ECM)
- ECM harness is open or shorted
- ECM circuit poor electrical connection
- Shorted sensor on 5 volt circuit
What does this mean? When is the code detected?
The Engine Control Module (ECM) has detected the sensor 5 volt reference circuit voltage is higher or lower than expected
Possible symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
P0641 Chevrolet Description
The control module has 2 internal 5-volt reference buses called "5-volt reference 1" and"5-volt reference 2". Each reference bus provided 5-volt reference circuit for more than one sensor. Therefore, a fault condition on one 5-volt reference circuit will affect the other 5-volt reference circuits connected to the reference bus. The control module monitors the voltage on the 5-volt reference buses.

Read more: http://engine-codes.com/p0641_chevrolet.html#ixzz31AP60YfR

Hi Ricky, I'm glad to help. Below is the possible causes for the P0344 code that you have.



Symptom:
P0344-CAMSHAFT POSITION SENSOR INTERMITTENT
When Monitored and Set Condition:
P0344-CAMSHAFT POSITION SENSOR INTERMITTENT

When Monitored: Engine running or Cranking.
Set Condition: When the failure counter reaches 20. One Trip Fault.
POSSIBLE CAUSES

GOOD TRIP EQUAL TO ZERO
WIRING HARNESS INSPECTION
(K7) 5 VOLT SUPPLY CIRCUIT OPEN OR SHORTED TO GROUND
TONE WHEEL/PULSE RING INSPECTION
CHECKING CKP SIGNAL WITH THE DRBIII
t LAB
CAMSHAFT POSITION SENSOR
(K44) CMP SIGNAL CIRCUIT OPEN
(K44) CMP SIGNAL CIRCUIT SHORT TO GROUND
(K44) CMP SIGNAL CIRCUIT SHORTED TO B+
(K44) CMP SIGNAL CIRCUIT SHORT TO (K7) 5 VOLTS
PCM

Fixya has no wiring diagrams due to copyrighting

P0652 DODGE - 5 Volt Sensor Reference 2 Circuit Low
These 5-volt reference circuits are independent of each other outside the PCM, but are bussed together inside the Engine Control Module (ECM). Therefore a circuit condition on one sensor 5-volt reference circuit may affect the other sensor 5-volt reference circuits. The ECM monitors the voltage on the 5-volt reference circuit.

Possible causes
- Shorted sensor
- Shorted sensor circuit
- Failed ECM

When is the code detected? The ECM has detected an out of voltage range on the 5 volt reference circuit 2.

Hope helps.

If you are getting a cam sensor code, it is not always the sensor. The code is just giving you imformation to what the ECM is seeing or not seeing.

The circuit needs to be tested. All the way from the ECM to the sensor.

You will need a wiring diagram and an explanation of how the circuit works to properly diagnose the problem.