While the 1990 Chrysler TC doesn’t technically have an OBD2 port (OBD2 wasn’t mandatory until 1996), it does have a diagnostic connector that serves a similar purpose. This article will help you understand why your 1990 Chrysler TC might not be starting and guide you to the location of its diagnostic connector. Several potential issues could be at play, ranging from a factory vehicle theft alarm (VTA) to fuel pressure problems, controller ground issues, or even a faulty throttle position sensor (TPS).
Common Reasons for Starting Problems in a 1990 Chrysler TC
If your 1990 Chrysler TC isn’t starting, it could be due to several reasons:
- Factory Vehicle Theft Alarm (VTA): While not common in 1989 models, a factory VTA might be present and armed. Try locking and unlocking both doors with the key to disarm it. A scanner can confirm if a “Theft Alarm” status is active.
- Aftermarket Alarm System Issues: Improper removal or wiring of an aftermarket alarm system can cause starting problems. Ensure all components are removed and factory wiring is properly restored.
- Fuel System Problems: Issues with fuel pressure or ignition can prevent the engine from starting.
- Controller Ground Issues: A faulty ground connection to the engine controller can disrupt various systems.
- Throttle Position Sensor (TPS) Issues: A TPS voltage above 2.50 volts at closed throttle or during cranking can put the engine in “clear flood” mode, preventing fuel injection. This won’t trigger a fault code; a TPS fault code only sets if the voltage is below 0.20 volts or above 4.80 volts with the throttle closed.
Diagnosing Fuel Pressure
Checking fuel pressure is crucial in diagnosing starting problems. You can rent a fuel pressure gauge from auto parts stores.
Multi-port fuel injection (MPFI) systems operate based on pressure differentials across the injectors. The injectors are exposed to manifold vacuum, so testing fuel pressure is essential. The wiring at the fuel pump and the Automatic Shutdown (ASD) relay might vary between model years (84, 85-87, 88-90, 91-up), but the testing procedure remains consistent.
Locating the Diagnostic Connector
The diagnostic connector on a 1990 Chrysler TC is typically located under the dash, near the steering column. It might be a single connector or a series of connectors. Consult your vehicle’s repair manual for the precise location and pinout information. This connector allows you to access diagnostic trouble codes (DTCs) that can pinpoint the cause of the starting problem.
Checking the TPS Voltage
To check TPS voltage, use a digital voltmeter and “backprobe” the signal and return wires on the TPS connector. Closed throttle voltage should be between 0.30 and 0.90 volts.
Conclusion
Troubleshooting a no-start condition on a 1990 Chrysler TC requires a systematic approach. Start by checking for common issues like a VTA or aftermarket alarm problems. Then, diagnose the fuel system, controller ground connections, and the TPS. Utilizing the diagnostic connector to retrieve DTCs can significantly aid in identifying the root cause. By addressing these potential problems, you can increase your chances of getting your 1990 Chrysler TC running smoothly again.
