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Driving in the dark... unless I force it!

4K views 24 replies 4 participants last post by  Leeb 
#1 ·
My 89 Seville has the twilight sentinel goody but it never seems to operate, and I get codes for it in history.

Diagnostic testing of the switch shows that the on/off/delay switch SEEMS to be working fine, but there is no light control...

Is the sentinel system built-in to the BCM or is it a separate box that can be replaced? I've checked all the fuses, so unless there is an external relay somewhere that's not kicking in, it is likely to be the control unit itself...

Wherever THAT is!
:want:
 
#2 ·
I used to have a 89 eldo and for the 10 years I had it the following three codes relating to twilight sentinel would not go away. It only bothered me because I could not figure out how to stop them - twilight sentinel worked fine all the time. A listing of the codes you are getting might bring you some help. My manuals went with the car but this bothered me so much I made copies of the diagnosis routines for these codes.

If you don't have manual PM me and I send you what I have.

B120 Twilight delay switch pot circuit

B121 Twilight enable switch circuit

B122 Twilight delay Panel timing
 
#3 ·
The major difference is that mine seems not to work at all.
I did not record the codes but these do seem to be those.... based on the 86 deville book I have, that is...

What had to be done to fix it? I'm beginning to wonder if the SOBs that put in the POS alarm system are responsible for this failure....

I have had it turned on recently, so maybe the codes are back. I'll get them and document them this time..
 
#4 · (Edited)
Eric got me the info... and thank you!

But...

It doesn't seem to cover the problem.
If I tell the BCM to cycle the sentinel, it kicks the lights on and off, but
it never does it on it's own....
Something's suggesting that the sensor may be faulty.

ANY CLUE where I find it? I believe that the IPC inputs show the status of the sensor (somewhere), but I don't know where to find it to see if it changes...

FIRST EDIT:thepan:
I found the BCC input entry for the twi photocell (under BCC DATA)... it shows a value of 4 at 0815 am...
I suspect it will not change tonite.
I also think I know where its at... under the defroster vent in the center of the dashboard...
There is a round 'capacitor' looking piece on the 'right side', and a small 'canister' looking thing on the left.
I THINK its the small canister-looking piece... but putting my finger over it does nothing...
and covering the capacitor with my hand does nothing either...:stirpot:

???
SECOND EDIT:thepan:
The BCC entry for the photocell showed a value of 5 at 9pm...
I don't know what that sucker SHOULD read, but I believe a difference of 1 is not QUITE enough...:rolleyes:
I guess I'll have to go to the dealer and buy one to find out 1) WHAT it looks like, and 2) WHERE to put the 'blessed' thing...:rant2:

Any other input would be GREATLY appreciated!:bouncy:
 
#7 ·
Hey. I just saw this topic maybe I can help. Behind the Headlamp switch you will find a bright blue screwed on. This is the twilight module. It receives reading from the photocell, and triggers lights on/off. Second, all late 80's cadillacs brought automatic courtesy lights. Meaning like the twilight, during the day with the sun out, the vehicle will not light the interior lights if the module receives anything past a 52% reading. If your windows are tinted, the photocell will send erratic signals, and set a code. Which is intermitten. Open your doors, if the lights come on, either the module is faulty, the sensor is lazy. Or your tints are causing the issue.

The photocell is smack in the middle of the dash board. If I recall correctly, either you have to remove the plastic cap on it's head, and the sensor is a plug in (much like a 194 bulb). Or you have to remove the radio, bezel assembly, reach in through the hole, and pull it out through the bottom. It's been a very long time. So I'm rusty. I do have a service manual for a 88 seville. Some differences with eldos, and devilles. But he twilight system is all the same. I can send diagrams and such as well if needed...
 
#8 ·
Miami-
If you could post a pic of what the sensor looks like it would help lots!

I think I know what you're talking about, and its held in place w/ a torx screw, so I should be able to lift it up enuf to work with it...

If it's just a plug-in as you said, then it should be fairly easy to do from above... I hope!

The interior lights do not operate at all unless I manually run them, but that is a secondary issue right now... since the sensor value is stuck at 4-5.... have never seen it move from there...
 
#9 ·
My problem seems to be a faulty photocell? It won't turn the lights on until it's pretty dark. There are no codes. The service manual claims you can simply replace the photocell mounted on the dash next to the sun/heat load sensor, but I have NEVER been able to find a replacement, including from Internet junk yards. :( Does anyone have a source? Thanks!
 
#10 · (Edited)
Go into diags and look at the BCM DATA for the photocell....
As I said above , mine sits at 4-5... and we're told it should span somewhere between 0-100...
Then shine a light on it and see if it changes... mine doesn't but I haven't tried anything else yet...

[FIRST EDIT]
Okay, I was right...
1) It is under the defrost cover on the left side, in a blue-colored (for mine, anyway) plastic case held down by (1) torx screw.

2) Once I disconnected it, the BCM DATA value jumpted up to 100 and the inside and headlights came on... I almost freaked out when I thought my DIC flourescents were failing (dimmed)!

It doesn't look like I can replace the photocell without damaging the case, but if I can manage to get it out, I may be able to find a replacement in an electronics catalog...

:thumbsup:
 
#11 ·
Leeb,

If it helps, the service manual instructions for removing the photocell are to remove the windshield defroster grill (it just snaps in and out), then remove the photocell by twisting it. The diagram shows it has a small electrical connector plug at the end of a short wire.

GM no longer stocks this part, my question again is, where the heck can you get a NOS or even a used one???
 
#12 · (Edited)
Well, mine didn't have any capability for 'twisting'...

But I have now 'removed' the cell from the mount, and once I can read the #s off it, I expect to be able to find something to substitute in its place...

It SHOULD be possible to get the resistance values and replace it with something close enough to operate correctly...

So far... so good!
:bouncy:

[FIRST EDIT]:stirpot:

If yours works but comes on 'late' check the top surface-mine has a 'mask' on it w/ a little hole in the center....

It is conceivable that, to get it to come on earlier, it would be easy enough to put a 'mask' (electrical tape or something opaque) with a smaller aperture than what it already has (or doesn't)...:stirpot:

Then all ya need do is wait to see when they trip!:bouncy:

[SECOND EDIT]:stirpot:
Stopped at the Cad dealer on the way home from work this AM. Said "I need the twilight sensor"...
"The one up in the dash?"
"That's it!"

He punched some numbers, and came back with the part in his hand.
55$ later I have a completely happy Sentinel system.:eek:

If anyone cares, the number for it was 1650-9958.
That was for an 89 Seville.... but they had it!:worship:

Now I don't feel QUITE so bad about that damn $200 antenna...:bigroll:
 
#19 ·
Hi Leeb,

Just checkin' in to see if you have any word on that photocell -- actually, if ANYONE has a chance to ask their dealer's parts dept. whether they still have one in stock and would let me know, I'd very much appreciate it (mine is long out of them). A lazy Twight Sentinel is a true pain...

Thanks!!
 
#22 ·
Sorry again... When I went by they weren't open for some reason...
I may have gotten there sooner than the last time.

Anyway,
yes, it IS jessup... Don't know who dare is.
The only other one I know of is Champion and I would be surprised if they didn't have it OR was able to get it too, but Jessup is where MINE came from.
Right off the shelf.
That was NICE!!
 
#25 ·
Glad to hear that!

Seems kinda funny, don't it, that you hafta call clear across country to get a part number for the guy next door...

But, I suppose, its better than driving here and back!

:)

I notice you said ORDER.... meaning they didn't have one.

The pigs!:rant2:

That is the same number as for my 89.... interesting.:suspense:
 
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