Help needed / Wiring Diagram for 1998 Viper GTS Map Sensor / P1296

[Motormax]

Hi Guys,

i´am Max, 30 years old and new to the forum here.

In this case it´s not about my own car, but from a close friend.

Car is a 1998 Viper GTS with a 2.4 Roe Supercharger.
Tuned via HP Tuners.
There is actually a longer story to the car, it had an engine failure two year´s ago due to a faulty ECU.
So the Car has a new ECU now. Bought from the Viper Store in Florida.
Good Service from those guys by the way!
Engine was rebuilt with OEM Parts ( Forged Pistons ) an is mechanically 100% fine.

Made around 650HP and 800 ft/lbs at the tires a few weeks ago on the chassis dyno. ( with WM running 10PSi, safe tune for pump fuel ).

Now about the problem:

The car currently has a Map Sensor fault. P1296 Map sensor supply voltage to low.
By backprobing the Sensor everything seems fine, good supply Voltage of around 5.1Volts while running and startup. Good ground and plausible signal Voltage.
We´ve also changed the map sensor already. No change...
The sensor used is the same 2 bar map sensor used in the SRT-4´s. The new sensor is a Standard Products AS220.
OEM Mopar is out of production... but both show the same fault anyway.
That´s the same sensor type that came with the Roe Kit when it was installed about 7 years ago.

Whats weird about the fault is, when you clear the code an start the car it´s fine. Also while driving, no codes.
As soon as you shut the car down and start it back up it runs like crap an throws the code.

If anybody has a pinout of the ECU i would appreciate it a lot, maybe there is a bad connection at the ECU?

Apart from that, anybody ever had that issue?

Thanks a lot already!

Best Regards
Max

 

[Goggles Pizano]

If rebuild why stock?

Was values changed in the tune?

 

[Steve-Indy]

Motormax, if you want, text your email address to me at 317-402-9013 and I will send to you the pinouts of the three connectors to the PCM (Powertrain Control Module) as shown in the 1998 Viper Service Manual.

 

[GunnsDonovan]

If anybody has a pinout of the ECU i would appreciate it a lot, maybe there is a bad connection at the ECU?

Apart from that, anybody ever had that issue?

Thanks a lot already!

Best Regards
Max

Try these out:

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[GunnsDonovan]

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[GunnsDonovan]

MANIFOLD ABSOLUTE PRESSURE SENSOR
The Powertrain Control Module (PCM) supplies 5 volts to the MAP sensor. Intake manifold pressure is a function of barometric pressure. The MAP sensor converts pressure into voltage. The PCM monitors the MAP sensor output voltage. As vacuum increases, MAP sensor voltage decreases proportionately. Also, as vacuum decreases, MAP sensor voltage increases proportionately.

During Key-On, before cranking the engine, the PCM determines atmospheric air pressure from the MAP sensor voltage. While the engine operates, the PCM determines intake manifold pressure relative to atmospheric pressure. Also, atmospheric pressure is updated at wide-open-throttle. Based on MAP sensor voltage and inputs from other sensors, the PCM adjusts spark advance and air/fuel mixture.

The MAP sensor mounts to the driver's side intake manifold plenum.

CIRCUIT OPERATION
From the Powertrain Control Module (PCM), circuit K7 supplies 5 volts to the Manifold Absolute Pressure (MAP) sensor. Circuit K7 connects to cavity A17 of the PCM connector.

Circuit K1 delivers the MAP signal to the PCM. Circuit K1 connects to cavity A27 of the PCM connector.

The PCM provides a ground path for the MAP signal (circuit K1) through circuit K4. Circuit K4 connects to cavity A4 of the PCM connector.

 

[GunnsDonovan]

Manifold Pressure/Vacuum Sensor: Testing and Inspection
To perform a complete test of the MAP sensor and its circuitry, refer to the DRB scan tool and appropriate testing and inspection procedures. To test the MAP sensor only, refer to the following:

CAUTION: When testing the MAP sensor, be sure that the harness wires are not damaged by the test meter probes.

1. Test the MAP sensor output voltage at the MAP sensor connector between terminals 2 and 3.
- With the ignition switch ON and the engine not running, output voltage should be 4 to 5 volts.
- The voltage should drop to 1.5 to 2.1 volts with a hot, neutral idle speed condition.
- If OK, go to next step.
- If not OK, go to step 3.
2. Test PCM Black terminal 27 for the same voltage described in the previous step to verify wire harness condition.
- Repair as required.
3. Test the MAP sensor ground circuit at sensor connector terminal 1 and PCM White terminal 31.
- If OK, go to next step.
- If not OK, repair as required.
4. Test MAP sensor supply voltage between sensor connector terminals 2 and 1 with the key ON.
- The voltage should be approximately 5 volts (±0.5V).
- Five volts (±0.5V) should also be at Black terminal 17 of the PCM.
- If OK, replace MAP sensor.
- If not OK, repair or replace the wire harness as required.

 

[GunnsDonovan]

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