Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Fault Codes 2/44420 & 2/44490: Communication/Rpm Signal Incorrect
1995 Saab 9000 CS, AutomaticSECTION Fault Codes 2/44420 & 2/44490: Communication/Rpm Signal Incorrect
- Connect Adapter Lead (8611048) and ISAT to Black diagnostic connector located under front passenger's seat. Enter ISAT command Code 281. Display should now show pulse length of load signal in micro seconds. At idle, this should be about 25 micro seconds and at full throttle about 500 micro seconds.
- To perform an alternative check, disconnect ISAT lead from diagnostic socket. Use ISAT PULS function to verify if there is a measurable change in pulse width and frequency at ETS ECU as throttle is increased.
- Exact pulse width and frequency that ISAT PULS function displays is not critical. It is important readings change with engine speed and load. If readings do not change, check White and Blue/Red wires between ETS terminal No. 27 and LH system ECU terminal No. 25 for an open circuit or short to ground.
- If wiring is okay, perform appropriate engine performance testing for LH system ECU. See appropriate article in the ENGINE PERFORMANCE section. If problem is still not found, replace LH system ECU and ETS ECU.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.