A Dodge Caravan's engine is a complex machine, and for every symptom of a problem that arises, there could be a couple of explanations. So, while troubleshooting a Caravan's engine sometimes only takes a good set of eyes while examining an engine, it still can be time consuming. The Caravan's On-Board Diagnostic system can streamline this process and cut out a number of false leads. How to use the OBD system depends on the year the Caravan was manufactured. The second generation of engine diagnostics became standardized in 1996. Caravans before that year use a totally different process.
Plug an OBD-II scanner into the Caravan's diagnostic Data Link Connection. The DLC outlet will be located beneath the driver's side dash and somewhere between the gas pedal and the left side kick panel.
Consult your scanner's user manual for the exact process. Button and faceplate orientations differ by brand of scanner, and so does the command entering process. Some scanners will switch on once sensing an incoming data stream from an OBD-II system. If you do not own this type of scanner, you will have to press the power button and turn the device on.
Turn either the Caravan's engine or the electrical system on. Your scanner device will require one or the other. If your scanner is not pre-programmed to retrieve OBD-II codes, you will have to key the appropriate button and enter a "Scan" or "Retrieve" command.
Read through the codes your scanner device retrieved. Some may be designated as "trouble" and some may be designated as "pending." Make a list with the trouble codes at the top and the pending codes at the bottom. Leave ample space next to the alphanumeric codes for later use.
Turn the Caravan's engine and/or electrical system off and remove the key from the ignition. Consult your scanner's manual for the OBD-II generic trouble codes. If the codes on your list are not defined in the manual, then you will have to look up Chrysler's supplemental OBD-II codes online. The Caravan's owner manual will not contain that information. Once you have found all the relevant code definitions, copy them onto your list next to the appropriate codes.
Return to your Caravan and open the hood to the engine compartment. Start with the trouble codes first, as they have happened frequently and set off your check engine light. Cross out codes once you have eliminated them from consideration. Then, move onto the pending codes. If you still cannot locate the problem, consider taking the vehicle to a Chrysler-approved mechanic.
Insert your key into the Caravan's ignition. Within the span of five seconds, turn the key back and forth in the following sequence: ON-OFF-ON-OFF-ON.
Watch the check engine light. It will begin to start flashing code at you. Count the flashes. Chrysler's OBD-I flash codes are sets of two numbers. The first number will flash, and a short pause will follow before the second number flashes. So code 38 will be three flashes, a pause, and eight more flashes. There will be a longer pause between code sets. Write all of these numbers down.
Turn the Caravan's electrical system off and remove the key from the ignition. Exit the vehicle and sit behind a computer. You will need to find Chrysler's OBD-I codes, and the owner's manual will not have them. Once you locate code descriptions, jot them down next to code numbers your recorded in Step 2.
Return to your Caravan and pop the hood. Investigate every code on your list and cross them out once they have been eliminated from consideration. If your list does not provide an answer and you are stumped, seek out a professional mechanic.
