Write-Up: Replacing Twilight Sentinel Photo Cell

write-up: https://rivperformance.editboard.com/interior-f20/write-up-replacing-twilight-sentinel-photo-cell-t4581-45.htm#110387

I was wondering, if anyone has had any issues with there twilight sentinel? ( I own a 95 S/C RIV)Irregardless of the position of the switch, the lights will not automatically turn on. Im just looking for insight before I change the photocell.
Thanks alot for your opinions.

Find one in a junk yard to test with. New one I believe around $65. Mine was not coming on soon enough so that is what I did and that fixed it but I don't think they normally go bad. Hope this helps

How do you change the photocell?

Photocell on top of dash in center by a/c sensor. It is a pain because the windshield is so close. I think I lost a wrench up there and never did find it. Be careful you don't drop anything down defroster duct. I think any tool I would use up there I would tie a string to it.

Wonder if it's possible/practical to remove the dash pad before working on that sensor?

Albertj

Remove defroster grille, twist socket 1/4 turn, unplug photo cell from socket . The a/c sensors are on either end of dash

Dumb question, but how does this automatically turn your headlights on? Don't you always have to physically pull the knob out for them to come on? I remember the GTP had auto lights but it had a clicker switch I think. When you took the emergency brake off, the headlights came on automatically.

The Riv has a sensor mounted in your dash that detects light (photocell) and activates the headlights at dusk.
If all is working correctly.

I've never manually turned on my headlights in 2+ years. Okay, maybe once.

Let me elaborate a little. Think of the Photocell as a small solar panel. It turns the Ambient light into an electrical signal to the twilight sentinel, which monitors that signal and when it falls below a set parameter, the twilight sentinel gives the LCM the go ahead to turn the headlights on. This is provided the car is running, the e-brake disengaged, and everything is functioning properly.

At least thats the way it was explained to me.

Thanks for the help guys. The dashboard has neveer been into I beleive, just because of the low mileage and, I purchased the car from a original owner senior citizen. Yes all the light and the rest of the (bells and whistles) all work well. I will check up on what was posted for help in the morning tommorow, and get back with an update.
Thanks again for the help.

JD94SS,
Did you get an owners manual with the car ?
The reason I ask is that you have to turn the sentinel on very simply. Some people don't know it exists. Not trying to insult your intelligence but you do know how to operate it, don't you ?

Wait, I think mine does have it it's just broke. My dad said it's been broke for some time (I think). How do I tell if I have it? If so, what is broke on my car - what do I need to replace? I'd love to never have to pull that stupid little knob out again! I wasn't aware the Riv was supposed to be just like the GTP - I thought it was only that way because it was newer.

I don't think it was optional, I think its standard on all Riv's. Check your owners manual on how to operate then report back with what you find it is and isn't doing.
In the meantime I'll look and see what the FSM says about it.

Is this it?

Spoiler:

I thought it operated based on where you put that little slider underneath the headlight knob. I've tried both ends and it does nothing. If I go out when it's pitch black and start the car and put it in drive as if to drive away, nothing happens. The car acts like it has 100% manual headlamps. I always thought it was supposed to be this way because I noticed if you ever try to leave the headlights on it dings at you very quickly and you know that you forgot to turn them off.

Please let me know how I can fix this, I'd love for them to be automatic (Especially if they're supposed to be). I always thought this was only on newer cars.

Sorry,
I haven't had time to look thru the manual for you today.
But I will post here when I can, I promise.

The slider under the headlight knob changes the amount of delay the lights stay on when you park the car at night.

The twilight sentinel operates using a sun sensor on the dash that tells the headlight control how bright it is out and how fast the brightness is changing (it does not, however, tell the headlight control how bright you are... you have to do that). For some reason the owners manual says you should use the headlight switch anyway, my guess is that has something to do with how it's calibrated or with a known/frequent failure mode.

Anyway... the fix would involve getting a wiring diagram from the FSM and doing manual diagnostics. My guess (and this is only a guess) is there's a short somewhere.

Explanation: the sensor is a photocell, which will decrease its resistance when exposed to light. [some photocells actually produce a small current when so exposed... but I digress...] The change in resistance [or current] is a function of light brightness.

Back to the point: So if your twilight sentinel is not turning your headlights on, one possibility is that there somehow is a short across the photocell (no resistance). So it thinks the sun is always shining. Consequently you might be looking for a chafed, busted or repaired wire that's shorted across the sensor. Depending on how the lighting system is configured, it may be the case that something is simply disconnected or bypassed - I really do not know.

Good luck

Albertj

Uhh, wouldn't this mean taking the dash apart?

Yes Rickw, I did get a manual with it. I did look at the procedure on how it is suppose to function. Ended up going to the junkyard and grabbing a photocell. Put it in and the lights are functioning as they should. Thanks for the help again guys.

Yea! I like not having to turn the lights on.

JD94SS wrote:

Yes Rickw, I did get a manual with it. I did look at the procedure on how it is suppose to function. Ended up going to the junkyard and grabbing a photocell. Put it in and the lights are functioning as they should. Thanks for the help again guys.

So are you talking about that little black bump on the dash? You replaced that?

Rickw wrote:

I don't think it was optional, I think its standard on all Riv's.

It was optional.
I have a friends '95 here that is the most basic Riv I have ever seen, his does not have the Twilight Sentinel. It has the bench seat, it's leather and I think the leather seat is the only thing optional it has?

Yes, I replaced the photocell. It failed when I tested it exposing it to light and to no light.

Glad you found the problem. I admit, I've never seen a photocell that has actually failed.

albertj

Yea, I know what your saying, I think I have maybe changed a handful, not even since, I have been workling.