Write-Up: Replacing Twilight Sentinel Photo Cell

Just finished replacing the twilight sentinel photocell on my 97 Riv and thought I would provide a few tips-and-pics for someone else that may need to do this:

1. The part number for the replacement photocell is 914032. (I purchased it from shopgmparts.com for $38.18 plus $9.95 shipping.)


2. To prevent tools and parts from accidentally disappearing down the defroster grill, cut two pieces of cardboard to fit around the front and sides of the photocell, making sure they fit all the way forward butting-up against the windshield.


3. With a small flat-tip screw driver placed just under the lip of the cell’s top hat, very gently and evenly pry-up the defective photocell from its socket. (When I did this, the photocell was so old and brittle that it cracked the top hat portion off and I had to use a sharp-pointed tool to pull what remained, out of the socket.)



4. Note the orientation of the exposed photocell socket terminals.


5. Using long needle-nose pliers, place the new photocell over the socket making sure the photocell terminals line up with the socket terminals. (The photocell is not polarity-sensitive and can go either way.)


6. Once the photocell is aligned in the socket, release it and press down on the top hat portion with your finger to make sure the photocell is fully seated.


7. If testing the twilight sentinel system during the day, place a piece of cardboard over the new photocell to fool it into thinking it is dark outside.

8. Start up your Riv, and with the interior headlight switch pushed-in (OFF), note the headlights, etc. and the interior instrument panel lights should come ON.


9. Remove the cardboard and note that very shortly your headlights and instrument panel lights go OFF.

10. Now have someone assist you by placing your Riv in NEUTRAL (or any gear other than PARK) and note that your headlights are OFF and your daytime running lamps (actually your bright headlights only) are ON.


11. Hopefully now your twilight sentinel system is as good as new. If it's still giving you problems, check the Lamp Control Module and/or instrument panel Headlight Switch.

Hope this helps!

Rivlanta wrote:

2. To prevent tools and parts from accidentally disappearing down the defroster grill, cut two pieces of cardboard to fit around the front and sides of the photocell, making sure they fit all the way forward butting-up against the windshield.

Now THAT is uncommonly common sense!

Great writeup, Craig, deserving of the coveted "Green Ribbon" (+)

New guy here. The Riv. is my wifes' ride, but I get to drive it now and then 'cause I get to maintain it. Lately (last 5-6 months) the headlights have been acting up. The lights would progressively take longer than normal to come on in the evening. Then, driving under lit up portions of the road they would shut off. The dash lights would remain on, but I would have to pull the light switch to get the headlights to come back on. Last Saturday, coming back from a trip, on a pitch black night, on a two lane hi-way, dodging deer, going around a curve, everything went black, headlights,and interior lights. Seemed like forever as I hit the brakes and went for the switch. Got lights back on while luckily staying on the road. My searching shows that it could be a few things, with the Light Contol Module being one possible place to look. Any suggestions, trouble-shooting ideas or any help woiuld be greatly appreciated! I am just glad that my wife wasn't behind the wheel.
Regards, Rick

Sounds like your Ambient Light sensor might be going (is) bad. It's that little bulb lookin thing in the middle of the dash pad. That lil guy is responsible for detecting proper lighting conditions for the Auto lights to go on and off; The LCM turns 'em on and off via that sensors' input.

Abaddon, if it is the culprit, what does the r&r entail?

Good to know. Great question and info! Are Ambient Light Sensors available?

If you have the light switch pulled out, will the lights cut out like that? Or is it just when you have the Twilight Sentinel feature enabled only, with the light switch pushed in? I'd hope it's just the 2nd case.

IBx1, 2nd case.
Rick

BMD wrote:

Good to know. Great question and info! Are Ambient Light Sensors available?

...last I checked they were, which makes sense as they are used in many GM cars and have been since the '90s. An FSM helps for R&R but it's not difficult - the moderator moved this post, look backwards and you will find the write-up.

In the meantime remember to use the light switch... if you have to replace the lighting control module, should be able to get a good one from a junkyard (try moradpartscompany.com) for low price.

Albertj

MTRiviera wrote:

Abaddon, if it is the culprit, what does the r&r entail?

The repair procedure simply states that the Sensor twists out counter-clockwise, kinda like a headlight bulb. It's just a twist-lock socket. Unplug the connector....reverse procedure.

The GM P/N is 914032. Lists as about $60. The P/N may have been updated by now, but any dealer parts guy can help you with that.

I just replaced mine last year, available from the dealer (recommend an on-line dealer for best price, like monsterpartsonline.com). The installation was easier than I thought it would be. The sensor doesn't unplug when you twist it out like I was expecting - once you have brought the sensor up out of it's socket, it unplugs and plugs in like a little 194 light bulb. I was looking for a plug on the wires... not there!

Great info! I will give this a try and hope that it cures my head light issues.
Regards

Abaddon wrote:

MTRiviera wrote:

Abaddon, if it is the culprit, what does the r&r entail?

The repair procedure simply states that the Sensor twists out counter-clockwise, kinda like a headlight bulb. It's just a twist-lock socket. Unplug the connector....reverse procedure.

Ahhhh... That would explain why Rivlanta broke his old one at the top of the page.
(Though I gotta' wonder how the hell you're supposed to get a grip on it that close to the windshield.)

Well, actually no, I knew it didn't twist from the prior posts. It just broke when I lifted up on it with the needle nose pliers. It was very brittle so that's why I suggest you lift very carefully.

It is a tight squeeze, but do-able.

I understand that the sensor plugs straight into the socket, like a 194 bulb, but also like a 194 bulb
the socket has a quarter-turn mount to the grillwork.
I just looked it up, and the factory instructions are to pop out the defroster grill, unscrew the socket
& push it through, and then remove/replace the sensor...

Specifically, the assembly instructions read:

# Partially install the sensor.
# Connect the electrical connector.
# Install the sensor to the defroster grille.
# Turn the sensor a quarter turn in order to secure.
# Install the defroster grille.

this might already be asked. I'm ordering a new sentinel...but what are the two black bulb like projections on the dash there...both sides????

Gracias!

I think these are photocells as well, but they connect to the HVAC system, to control how much air is routed to each side of the car. My parts list says they are: GM #16146093 "Sun Load Temp Sensor"

weird...well I guess they work as I'm cold all over the car now!
Thanks!

There seems to be a lot of back and forth regarding whether or not you pry out or need to give the sensor a twist when removing it. What's the real census on that?

I just changed mine. It pops out. No twist at all. It's like a side marker light...just pushes into the socket. No twisting at all...

oops,posted twice

Twice the reassurance haha thanks!!

Lemme just say it was easier to change the rear plugs in this car than to change this sensor. In fact, the half broken one is still stuck in the dash right now. Will have to just remove the upper dash and defrost grill to even get at it I suppose... why always the designs for people with 4 year old's hands and 4 foot long arms?

llamalor2112 wrote:

Lemme just say it was easier to change the rear plugs in this car than to change this sensor. In fact, the half broken one is still stuck in the dash right now. Will have to just remove the upper dash and defrost grill to even get at it I suppose... why always the designs for people with 4 year old's hands and 4 foot long arms?

Let's just say replacement was not expected to be frequent... this is the same car, mind you, on which you have to remove the entire rear sweepspear (taillight housing) in order to replace a bulb. And don't even start in on the headlights...

I know what you mean. At least those pieces are accessible via fasteners, if not awkward ones. The ones I hate are the parking lights, when one goes out I have to buy a new set of well trim clips because the old ones don't like to hold as strong the second time! Haha It's like everything else on nicer buicks, planned obsolescence of parts to ensure return to the dealership under warranty instead of outside practices. That's been what I can gather. I don't imagine I'll need t o change the twilight sentinel for a good while at least though. I just get so frustrated with tight spaces like that