QuestionQUESTION: Recently the instrument cluster has been erratic with the engine off and the key removed--gauges fluctuate, little blue lights come on and off, etc. Replaced defective battery and now when the key is shut off and removed or left in, the various gauges are flat lined but randomly jump and fluctuate. In a completely quiet environment I can hear what sounds like a small blower running.
Thanks for your consideration
ANSWER: Hi Don,
It may either be electronic noise in the power supply to the cluster or malfunction in the digital data system that brings info for the gauges, of the cluster itself. I would start with the cluster which has a self-test capability:
With the engine OFF press the trip and reset buttons.
Then while holding the buttons turn the ignition switch to the ON position
Continue to hold the buttons until the word
CODE appears in the odometer window, then release the buttons. If a problem exists a trouble code will appear, or in no problems then a 999 will appear. When chec-0 appears the lights should dim slightly in the cluster, if not then there is a problem in the cluster.
When chec-1 appears the gauge pointers will start to move. The tach should show 0, 1,000, 3,000, and 6,000. Chec-2 tests the odometer segments, and Chec-3 tests the transmission position indicators. Let me know of any 3-digit codes that appear.
On the power supply, although the key is off the voltage to the two fuses that power it is still on. Fuse 28 in the under the hood power box maintains the memory function and fuse 2 under the dash operates the rest of the cluster. There are a couple of diodes in the dash box that are in the current pathway for the fuse 2 supply. Let me know if you have a volt-ohm meter and I can tell you how to test those for failure which could let noise into the cluster.
The digital data bus is a challenge to test and remediate.
The only small blower that I am aware of is one associated with a heater/ac control unit that is of the automatic temperature control type (with digital readout) but if you don't have that sort of unit then I really don't know of another such blower source.
I'll wait to learn what you find. Does the cluster work OK when you are driving the van?
Roland
---------- FOLLOW-UP ----------
QUESTION: Roland---thanks for such a prompt reply---you are great!!
I followed your suggestions/instructions and here are the results.
The cluster self test did everything you indicated---fortunately or unfortunately the only code was the 999 but it did all the other steps.
I did remove and check the two fuses---both checked good. I cleaned them and sprayed a bit of contact cleaner into the sockets and nothing has changed. One unusual item of interest is that when I removed fuse 28 from the hood power box, the little blower sound and the erratic behavior of the gauges stopped. I inserted the key and the blower sound came back on and the gauges started jumping. Removing the fuse again silenced the sound and stopped the gauges from jumping. Fuse 2 did not have a similiar affect.
The cluster does operate perfectlty while driving although before I replaced the battery it acted up driving and then included the displays turning on and off. Another note is that after getting a new battery installed yesterday the cluster was quiet and stable when I first got into the car and after I drove it home. It was normal this morning until such time as I inserted the key.
I do have a multimeter and may be able to check the diodes. I am also up in the years and not as limber as I would like to be but I am willing to give it a try.
Unfortunately my wife is going to take the car for several hours and I probably will not have a chance to do much more until morning.
Another note is that I was looking at the owners manual and there is a section entitled "vehicle storage" and it recommends removing fuse 28 if the car will be stored for more than 3 weeks inorder to protect the battery. Apparently one of the functions of that fuse is termed--IOD (ignition off draw)---what ever that means. Thanks again for your help and I'll proceed with any other suggestions you have as soon as I can.
don risavy
AnswerHappy New Year, Don!
May I ask for your help?
I need your vote of confidence.
I'm in a close race to be recognized as 'Volunteer of the Month' at Allexperts
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Please click on "Thank/rate the expert" button below/left
It will take you to a page which asks "Would you like to nominate this expert...?"
Click on the "YES"
That's it.
Thanks for taking a moment to help a fellow Chrysler-owner.
Roland
PS:Do it now, the contest closes at 6pm central time.
Hi Don,
The IOD fuse does indeed provide current to many items around the dash: the cluster, the body control module (located on the back side of the fuse box under the dash, and through it the interior lights), the remote keyless entry module, memory seat/mirror module, the message center, the radio (preset memory), and to fuse 2 as well in off-run-start positions (which provide power to the transmission control module). It could be that you hearing the humming of the body control module.
As for the diodes, the 'hot' side of fuse 2 (remove it to verify which clip is hot) is fed current through to diodes in parallel that are attached to pins 15 and 31 of the black 36-pin plug which is one of four at the top edge of the under dash fuse box. If you removed the plug and then measured the resistance between each of those pins and the 'hot' clip of fuse 2 you should find that the resistance readings will differ depending upon which polarity you apply to the measurement with the leads of the ohmmeter, IF the diodes are OK. I have not tried this myself but that would be my understanding of what to expect to be the behavior of a diode.
The current through fuse 28 (with fuse 2 installed) and the plug back in its socket may be found to run about 500 mA for about 1/2 hour, but then the TCM shuts down and the current should drop to around 25 mA, should your meter be equipped to measure such currents. So that would be a test of the overall draw of the IOD circuit.
I would not be too concerned about the gremlins showing in the cluster in the shutdown condition if the off draw current is normal.
Roland
