Expert: Roland Finston - 12/22/2011

Question
QUESTION: My 94 Chrysler LHS overhead travel information center does not turn on. I checked the fuses and the wiring inside the unit but still can turn it on. Is there a way or do you have any suggestions on why?

Thank you

ANSWER: Hi Roger,
The OTIS has four wires: the dark blue/white should show 12v when compared to the black/light green wire which is the ground, when the ignition switch is in the 'run' position. If you have that, then there is something wrong inside. If you don't then check fuse #14 in the box behind the left end cap of the dash (5 amp). Let me know if you have voltage across the fuse but it doesn't get to the center as there is either a break in the dark blue/white or the ground wire
You could check for continuity of the ground wire to a shiny chassis metal, and similarly check for 12v on the dark blue/white to a chassis ground with a volt-ohm meter. Look carefully at #14 for a subtle crack in the wire inside of it.
Roland
PS Please 'rate' my answer, and where you see the question about a nomination of me to be 'volunteer of the month' consider giving a 'yes' response. Thank you

---------- FOLLOW-UP ----------

QUESTION: I have followed your advice and I do have power to the dark blue/white wire. Can the OTIS be turned off or on? If not then the unit is fried, right?

Thanks & merry Christmas

Answer
Hi Roger,
It appears that the off/on function is driven by the digital data bus wires, so let us check out those as well: the most accessible and relevant location might be the body computer hidden behind the rug covering the right kick panel (under the dash, immediately in front of the door opening).
The white/black and the violet/brown wires are found on the bone colored plug at the bcm on pins 7 and 8 so you should be able to measure across from the bcm to the overhead console with your meter leads. If you find there is continuity in the two wires, then presumably the digital message is arriving at the console. The other thing to try is to simultaneously depress the CT and Step buttons and hold them, then turn the ignition key to the run position and see if the unit lights up. I assume you also verified that the there was 12v shown between the other two wires at the console to verify that you really had a ground wire connection as well.
The laat thing to do would be to examine the circuit board for the center to observe for any wet capacitors or loose wires.  
That pretty much exhausts the possibilities. Good luck!
Best of the holidays to you as well.
Roland
PS Thanks for the '10' ratings of my first answer. You have another opportunity to give me a nomination for volunteer of the month if you will press the 'rate the answer button'. Thank you.