Chrysler Repair: 98 caravan climate control, dodge caravan, battery cables

Question
i have recently purchased used 98 dodge caravan. everything works great except the ac and rear wiper lights keep flushing. someone has told me that it was controled by the computer and it needs to be reset. that it was a simple procedure of presing and holding climate control buttons in specific order. do you know if thats so and what is the procedure?


Answer
Hi Mark,
This question came up earlier this year, and fortunately another owner sent me an explanation which I copy here:
"Hi Roland,

No question. Just passing on to you info for the person with the Town & Country with the two lights flashing on the HVAC head unit. This is a fairly common phenomenon on the 96-00 minivans.

To make it stop, you can just make the body control module run the diagnostic sequence. You start the engine, setting temp to cold, with fan on high, and pushing the rear wash and rear wiper buttons at the same time and holding them until a bunch of lights start to flash.

It takes a minute or two for the tests to cycle through. It'll run the calibration/diagnostic test (2 lights flashing) then the cooldown test (2 other lights flashing). If all passes, the rear wiper switch will flash alone. Push it to exit tests.

If it fails, one of the lights on the head unit will flash out a diagnostic code, just like the OBD does with the SES light. There's about six pages in the Chrysler manual about what the HVAC diagnostic codes are, but I have no clue what they are. I don't own a manual, but it was shown to me once.

Your advice was correct in that the questioner's HVAC system is probably fine. However, this phenomenon of the lights flashing can happen when the BCM experiences a spike or dip in power. You might want to ask the questioner if he recently removed or replaced the battery, or something in the charging system. If not, he may want to have his battery and/or alternator tested. He could have a dying battery, corroded terminals, bad ground, failing battery cables, etc., etc.

The BCMs in these vehicles, I have found, are very similar to the computer in your home or office, in that they like clean, steady power, and begin behaving badly if there are surges and power losses. Also, a soft reset of the BCM, by pulling the IOD fuse or negative battery cable for five minutes will clear out anomalies, glitches and other little hiccups, much the way a reboot will free your home or office computer from being caught in a data loop.

Rick"

So this should help you move ahead on this problem.
Roland