1990 courtesy light problem
Thread Starter
Race Director
Joined: Mar 1999
Posts: 12,586
Likes: 237
From: Bartlett Illinois
1990 courtesy light problem
I have an odd problem and it is not really in the Helm manual (that I can find)
the Courtesy lights work, VIA headlight switch or opening a door, hatch etc. where it is not working right is when you shut the doors, the lights go out immediately, no delay. How do you test that? what do you check?
another thing is the backlight for the cluster is not always on with the key, like the 91 dash in my 89, the photo sensor seems to be working.
I have a spare photo sensor I could swap for grins, but just curious if anyone has suggestions on what else to check.
the Courtesy lights work, VIA headlight switch or opening a door, hatch etc. where it is not working right is when you shut the doors, the lights go out immediately, no delay. How do you test that? what do you check?
another thing is the backlight for the cluster is not always on with the key, like the 91 dash in my 89, the photo sensor seems to be working.
I have a spare photo sensor I could swap for grins, but just curious if anyone has suggestions on what else to check.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
You have a defective courtesy light delay timer.
If your backlight doesn't always come on with the ign in run, then what conditions does it come on? Is it intermittent? Try turning the headlight switch fully counterclockwise for full backlight brilliance.
If your backlight doesn't always come on with the ign in run, then what conditions does it come on? Is it intermittent? Try turning the headlight switch fully counterclockwise for full backlight brilliance.
Thread Starter
Race Director
Joined: Mar 1999
Posts: 12,586
Likes: 237
From: Bartlett Illinois
the backlight comes on with the parking lights, dimmer the parking/headlight switch works, as seen on the cluster. so it does turn on with the parking lights and works dim to bright.
I also found that the light light up with a flashlight shining on the photosensor, with the flashlight the cluster goes full bright (ambient A/D counts 0) if I remove the light and cover it, the Ambient sensor A/D counts are 240. per the GM Service manual the Ambient light sensor works.
As for the courtesy light if the 'delay timer' is bad I am not goign to worry, since the 90s delay timer is built in the CCM as far as I know.
Another thing the manual states is, if there is light, the courtesy lights will not stay on. as the ambient sensor controls them. I know someone else with this SAME issue, anyone here have the same issue with their 90 newer? the other guy with this issue I know of is stumped like I am.
Thread Starter
Race Director
Joined: Mar 1999
Posts: 12,586
Likes: 237
From: Bartlett Illinois
dimmer slide on the left side of switch, fully clockwise turns fukll bright and switches the courtesy lights on, if you go far enough, full counterclock wise, full dim.
Again, this works when the parkign lights are on. the cluster backlight I thought was always on with key on. I will check a few more cars this week. but that is how it works on my 89 (with 91 dash) it sounds like the issue might be in the CCM, but all test so far say the circuits/functions are fine
At this point I just want the cluster to be abel to be seen when driving without having to turn on the lights, I am not concerned about the courtesy delay..
Another thing, the Radio LCD acts alogn with the Cluster LCD/gauges..
There are NO CODES in the CCM as well
Thread Starter
Race Director
Joined: Mar 1999
Posts: 12,586
Likes: 237
From: Bartlett Illinois
to add,
I will try the dimmer switch on the cluster tonight with no parking lights on, but I am pretty sure it does not work that way in its current state.
oh yeah, another thing, key off, parkign lights on I don't the gauges light up either and I thought they should
I will try the dimmer switch on the cluster tonight with no parking lights on, but I am pretty sure it does not work that way in its current state.
oh yeah, another thing, key off, parkign lights on I don't the gauges light up either and I thought they should
Team Owner
Joined: Sep 2003
Posts: 25,366
Likes: 2,733
IP lamp dimmer
Jeff,
There's a lamp dimmer module behind the instrument cluster I'm quite sure that "fixes" multitudes of problems and is used on most GM products late '80's through the '90's. 1995263 should be GM#. The FSM calls it "incandesant lamp driver". I've never had a situation of my own so I can't help you with diagnostics but it's likely where I'd start.
There's a lamp dimmer module behind the instrument cluster I'm quite sure that "fixes" multitudes of problems and is used on most GM products late '80's through the '90's. 1995263 should be GM#. The FSM calls it "incandesant lamp driver". I've never had a situation of my own so I can't help you with diagnostics but it's likely where I'd start.
Thread Starter
Race Director
Joined: Mar 1999
Posts: 12,586
Likes: 237
From: Bartlett Illinois
Jeff,
There's a lamp dimmer module behind the instrument cluster I'm quite sure that "fixes" multitudes of problems and is used on most GM products late '80's through the '90's. 1995263 should be GM#. The FSM calls it "incandesant lamp driver". I've never had a situation of my own so I can't help you with diagnostics but it's likely where I'd start.
There's a lamp dimmer module behind the instrument cluster I'm quite sure that "fixes" multitudes of problems and is used on most GM products late '80's through the '90's. 1995263 should be GM#. The FSM calls it "incandesant lamp driver". I've never had a situation of my own so I can't help you with diagnostics but it's likely where I'd start.
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