Jonny, I found this in my shop manual, section 11 (Electrical System) It's from an '02 manual, but it may point you in the right direction.
Information Center Verification
The BLACK wire is the ground. The RED/PURPLE wire is the 12 Vdc from the battery. It is protected by a fuse on the MPEM; the
fuse “MPEM” and the fuse “ACC” on DI models. The accuracy of some features of the Information Center can be checked with a potentiometer.
Fuel Level
1. Disconnect the 4-circuit connector housing of the Info Center.
2. Using an appropriate terminal remover, remove the PINK wire from the tab housing.
3. Reconnect the connector housing.
4. Disconnect the 2-circuit connector housing which contains a PURPLE and BLACK wires.
5. Remove the BLACK wire from the receptacle housing.
6. Reconnect the connector housing.
7. Connect potentiometer test probes to the PINK and BLACK wires.
8. Adjust potentiometer to the resistance values as per following chart to test the accuracy of the gauge.
NOTE: The gauge must be activated to obtain a reading.
GTX 4-TEC
RESISTANCE (Ω) WET HEIGHT FROM
BOTTOM (mm)
4.8 ± 2.2 247 ± 5.0
17.8 ± 2.2 207 ± 5.0
27.8 ± 2.2 183 ± 5.0
37.8 ± 2.2 158 ± 5.0
47.8 ± 2.2 133 ± 5.0
57.8 ± 2.4 105 ± 5.0
67.8 ± 2.8 76 ± 5.0
77.8 ± 3.6 55 ± 5.0
89.8 ± 3.6 35.3 ± 5.0
I also came across this information concerning ECU and MPEM replacement.
NOTE: If the old EMS ECU or MPEM is working, it must be read inside B.U.D.S. prior to removing it from the vehicle to carry vehicle information and history to the new EMS ECU or MPEM.
Before replacing a MPEM or EMS ECU, always check electrical connections. Make sure that they are very tight and they make good contact and that they are corrosion-free. Particularly check MPEM and EMS ECU ground connections. Ensure that contacts are good and clean. A “defective module” could possibly be repaired simply by unplugging and replugging the MPEM or EMS ECU. The voltage and current might be too weak to go through dirty wire pins. Check carefully if pins show signs of moisture, corrosion or if they look dull. Clean pins properly and then coat them prior to assembling
as follows:
AMP connectors, EMS ECU connectors, OPS and OSPS connectors: Apply a thin coat of DEOXIT contact lubricant (P/N 293 550 015) Other connectors: Apply a silicon-based dielectric grease or other appropriate lubricant. If the newly replaced MPEM or EMS ECU is working, try the old one and recheck if it works. Ensure that all electronic components are genuine — any modification on the wiring harness may lead to generate fault codes or bad operation.
