Experiencing trouble diagnosing your 1997 Grand Caravan because your OBD2 scanner isn’t connecting? You’re not alone. Many owners of older vehicles, particularly those from the mid-90s, run into the frustrating issue of a non-functional OBD2 port, even when they expect to find one. This guide will walk you through potential causes and troubleshooting steps when you encounter a “97 Grand Caravan No Obd2” situation.
The first thing to understand is that while OBD2 became a standard in 1996, the transition wasn’t immediate and universal for all makes and models. Some 1997 vehicles, including certain Chrysler minivans like the Grand Caravan, might not be fully OBD2 compliant or might have early implementations that cause compatibility issues with modern scanners.
If your OBD2 scanner fails to communicate with your 1997 Grand Caravan, and you’re also noticing issues like an instrument cluster malfunction, a primary suspect could be the PCI bus (Programmable Communications Interface). In many Chrysler vehicles of this era, critical systems like the SKIM (Sentry Key Immobilizer Module) rely on the PCI bus for communication. If there’s a problem with this bus, it can disrupt communication across various modules, including the diagnostic system.
A lit SKIS (Sentry Key Immobilizer System) light on your dashboard, combined with no OBD2 communication, further points towards a potential PCI bus issue or a problem with the SKIM itself. Even with a SKIS error, the engine might still crank, but the system will likely cut fuel and ignition after a couple of seconds, preventing the van from starting.
Starting problems in conjunction with no OBD2 connectivity can also lead you to examine the vehicle’s computer (PCM or Powertrain Control Module) and its related wiring. The starting system in these vehicles is somewhat complex, incorporating features like double-start protection and a clutch interlock switch circuit (though less relevant for an automatic transmission Grand Caravan, it’s still part of the overall system logic). Issues within the PCM or its wiring harness could prevent the engine from starting and simultaneously affect communication with the diagnostic port.
Before diving into complex diagnostics, consider any recent repairs or modifications. For instance, if you’ve recently worked on the Throttle Position Sensor (TPS) harness and disconnected computer connectors, double-check that these connectors are correctly reconnected. It sounds simple, but mistakenly swapping connectors can disrupt communication and prevent the car from starting or communicating with a scanner. Pay close attention to any color-coding or markings on the connectors to ensure proper matching.
Also, think about any aftermarket accessories or modifications to your Grand Caravan, especially electrical add-ons. Even something as seemingly simple as an aftermarket head unit can sometimes interfere with the PCI bus if not properly installed, as the factory radio harness often includes PCI bus connections. Similarly, consider if the vehicle has been in an accident or undergone any significant repairs that might have affected the wiring harness.
If a dealer has already attempted diagnosis and couldn’t resolve the issue, it might be time for a more hands-on approach. Investing in a digital multimeter and obtaining a factory service manual (FSM) for your 1997 Grand Caravan can be invaluable. The FSM, particularly the powertrain diagnostics section, will provide detailed wiring diagrams and step-by-step procedures for diagnosing no-start conditions and communication problems. This will allow you to systematically test circuits and rule out potential component failures, getting you closer to pinpointing the root cause of your “97 grand caravan no obd2” issue.
