98 Grand Caravan Electrical problems

[wilwsr]

Having elect problems and need advice before I replace BCM or ECM.
Symptoms:
-Interior lights, odometer, xmission indicator lights all flicker when egine is running(becomes worse if engine idles for long period).
-Sometimes speedodmeter and tach does not work
-Headlights flicker while engine is running
-No lights flicker while egine is off but are less bright
-Sometimes battery light or ABS light illuminates
-NEW battery, headlight switch, and altenator
-Altenator output is 14.2V
-Turn engine off and battery voltage drops to 10.8V within mins
-Slow starting due to low battery voltage
-Radio cuts out when high current items are operated(both power windows or door locks)
-Engine runs great, all accessories function


Read that the ECM, BCM and instrument panel are part of the voltage regulator function. Is that true? Please help.

V/R
Willie

[gforster]

Sounds like the voltage regulator in the PCM is shot (PCM is the one that controls the voltage; it;s under the hood) or you have a major short somewhere. I would have suspected shorted diodes in the Alternator but you replaced it. Check for fault codes and pay attention to any pertaining to charging targets etc. Good news is that you can bypass the regulator in the pcm with an older style mopar electronic regulator if the PCM is indeed shot.

Geoff

[aspelins]

Geoff,
Sounds like you're pretty knowledgable. Good thing. I've been in and out of the shop for the past two weeks. Do you think my problems are similar to the original post? Here are the symptoms from the past week and in weeks past from time to time over the past few months...
-speedometer, tach dim while operating
-radio goes on and off while operating
-Voltage light came on this morning
-dome light doesn't come on when door open
-took van to shop and couldn't replicate any of the problems

Battery seems to be ok and headlight switch has been replaced.

Last week I had these issues...
-van would not start - not even a turn but had crazy clicking noise coming from relay switch in driver's side
-removed relay that was clicking and noise stopped however problem is the same with relay in or out
-van started but died in a parking lot a few days later
-power locks wouldn't work so had to manually lock driver door... all power locks started going crazy and relay-type clicking started under the hood but eventually stopped
-had van towed to shop and they could not replicate any of the problems

Talked with the shop manager today and only thing they could think of would be to check and replace the computer. From what I hear that could lead to BIG $$$.

Any thoughts?? I'm new to all this car repair slang... can you give more detail on the PCM?

[gforster]

Hey you are just in luck.. I have a 96 Grand and just finished installing remote start on it this weekend. I had the negative battery terminal removed for safety, but I temporarily placed it loosely back on the post from time to time as I needed in order to check things during the install. One of these times I went to start and got nothing but I got the crazy relay buzzing and the door locks/interior lights going crazy! I just firmed the battery connection up a bit and it all stopped and worked fine. The buzzing is something relays do when they don't get enough current. You defenetely have a battery cable connection issue here. Check the grounds as well. You don't need a computer or anything else. If you still have probs have the battery checked. Lemme know what you find...))

Geoff

[emedlin]

Originally Posted by gforster

Hey you are just in luck.. I have a 96 Grand and just finished installing remote start on it this weekend. I had the negative battery terminal removed for safety, but I temporarily placed it loosely back on the post from time to time as I needed in order to check things during the install. One of these times I went to start and got nothing but I got the crazy relay buzzing and the door locks/interior lights going crazy! I just firmed the battery connection up a bit and it all stopped and worked fine. The buzzing is something relays do when they don't get enough current. You defenetely have a battery cable connection issue here. Check the grounds as well. You don't need a computer or anything else. If you still have probs have the battery checked. Lemme know what you find...))

Geoff

Thank-you, Thank-you, Thank-you!!! Your post hit the nail on the head. Before reading your post I just knew I had a short or bad control module. Trouble shooting these would have taken hours and could have cost many $$$. As it turned out I fixed the problem in ten minutes and it didn't cost a dime.

Yesturday my 1998 Dodge Caravan SE's instrument cluster started go crazy while driving down the road and was even worse while parked. After a little while the problem just went away. Drove fine all this morning then cut the van off and it would not restart. It would act just like a weak battery but voltage across the terminals was 12+.

Other symptoms I experienced were:
- interior and exterior lights were dim or not functioning at times
- could hear several relays clicking wildly when turning on ignition switch without even trying to start it
- sometimes relays and instrument gauges would still go crazy even after switch was turned off and keys WERE REMOVED
- windows would not go up and down
- power door locks would barely work, relays would click many times as lock slowly went down or up
- did get the car to start once or twice but the gauges and lights were going crazy and the radio had a cracking/popping noise especially when the engine RPM was increased

I found a very easy way to determine this as the cause:
- start with the engine off and the keys removed
- using a simple volt meter check the voltage of the battery on the posts; make sure you are firmly pushing on the lead posts and not any part of the cable clamps. You should get a readying of 12+ volts. If not, charge the battery 1st or have it checked out.
- now turn something on that will draw some current. I tried the horn and headlights as I could reach these while still holding the volt meter probes on the battery posts. If the battery is doing well you should see little change in the voltage maybe 0.5V to 1.0V at most.
- next I moved my probes from the lead posts to an exposed metal point on the cable clamps
- with nothing on I still got about 12V but it was about 0.25V to 0.5V less than directly on the posts
- finally I tried the horn again. This time the voltage dropped way down to about 6V. Of course this will vary depending on how bad the connection is. Obviously the current wasn't making it through the connection from the posts to the clamps.

The solution:
- disconnected both clamps from the battery
- cleaned posts and clamps with a wire brush and a corrosion cleaner/preventive (my personal favorite -- clean with paste of baking soda and water then prevent future corrosion with paste of baking soda and petroleum jelly)
- reconnected both clamps, making sure they are on tight
- no more problems, engine fired right up and everything else functions just fine


Again, Thank-you, Thank-you, Thank-you for leading me to this solution.

[ladymech62]

Lead type batteries are rather notorious about gassing and sulfating. A good cleaning with soda water and a wire brush do wonders. Sometimes the battery will gas so bad that you can have it corrode the wire harness connections nearby . . .

[musiq021]

I just had the clicking, flickering, and not starting problem yesterday. My terminals do look pretty grummy, I'll clean them tonight, and get back to you guys on the results.