Seat belt light not working - can't figure out why

Seat belt light doesn't come on like it's supposed to when turning the key on or starting the truck. I've swapped known working bulbs in the cluster. I'm getting power to the plug under the seat.

What else can I check?

I don't know when it stopped working but I have 2 possible thoughts on it.

1. I did swap the integration relay in order to get the ignition light ring to work. Could that have caused the seat belt light to stop working?
2. I did swap the cluster from a non-tach to a tach version. Could that be it?

I found a wiring diagram and it actually mentions w/ tach and w/o tach but I don't really know how to read it. What does the circled area mean below. Is the warning light pinned differently on the tach vs non-tach cluster?

 

Interesting

Electrical gurus here will have more precise answers

This is my advice that may/may not work
On older vehicles (like ours) there is a way to defeat the seat belt light/chime
Done this on Honda/Subaru in the the past
Simply buckle/release buckle/release several times (5-10 times in secession)
Defeats the system

 

Hmm, I wonder if that works. That sounds like the opposite of what I'm trying to do though. I'm trying to MAKE it work!

I found the old integration relay in the parts pile and that's an easy swap to test that theory. I still have the old gauge cluster too and the dash is already torn apart so I suppose that's easy enough to swap that too to see if it's the cluster. Definitely don't want to go back to not having a tach though so if it's a wiring difference, I want to figure that out.

 

Tacomas integration relays have to be replaced part number to part number. If you have access to the Toyota factory wiring manual the will show the internal wiring inside the intgration relay it should be kind of simple* to check inputs, througtputs and outputs.
*anything under the dash is a p.i.t.a. if you ask me.

 

Doesn't appear you have the correct wiring diagram for a 99 Tacoma, 99 doesn't differentiate between tach and no tach.
Have you verified the buckle switch works properly?

 

i don't have the wiring manual

Thanks for the one specific to 99! The one I had came from a different site and I assumed it was something that probably didn't change (damn assumptions!). Good to know I can probably rule out the cluster. i don't think it's the buckle because shouldn't the light come on regardless when starting the truck? i've unplugged the buckle at the connector under the seat and the light still doesn't work. That should mean it's something other than the buckle right? My understanding of that circuit is it's open so the light is illuminated and when the buckle is used the circuit is closed and the light goes off. Or do I have it backwards?

 

Service info says the buckle switch is open when the seatbelt is buckled so jump the 2 terminals at the buckle switch and see if the light comes on.

 

It's irrelevant to your troubleshooting at this point but might be interesting to you regardless: The 2001-2004 replaced the two-piece body fuse box/integration relay with a single "Body ECU". No idea how that affected the surrounding wiring.

If you haven't already, I'd put the original integration relay back in and see if that changes anything. The seatbelt light is controlled by the relay. I tried swapping relays in my truck as an experiment and found that the 2000 relay caused the seatbelt light to flash while my original 1998 relay kept it on solid.

 

aaaah, thank you! another thing to try.

your experience with the relays is interesting. swapping my old one back is on the to-do list for this weekend. When I originally swapped it, the one I used was listed to fit my year so I was hoping that differences would have been minimal.

 

Great info posted ireymon !

let everyone know results!!!!!

 

OK, I swapped the old int. relay and no change. light still doesn't illuminate. I jumped the plug and the light flashed. I have another (used) buckle I swapped in after a liberal dousing of brake clean (it was REALLY nasty) followed up by some MAF cleaner (it's all i had) and light still doesn't illuminate. I'm getting power out of the plug coming out of the carpet but the system thinks the circuit is open so the light stays off.

Could it be my buckle and the alternate buckle are both bad?

I did not swap the clusters because I don't feel like that's the problem.

Thoughts/suggestions?

 

Do you have a multimeter or other circuit tester you could use to check the buckles?

Since you first posted I realized that my truck might have a similar problem. I've noticed that my seatbelt light doesn't consistently work--sometimes it turns on, sometimes it doesn't.

It seems like you've narrowed the problem down pretty well. The dash light works, the integration relay didn't cause any apparent difference in behavior, manually jumping the plug on the cab harness causes the light to turn on reliably.

If it's not the buckle then the only other thing I can think of is maybe the circuit is more complex than we're assuming--maybe there are other conditions required for the light to turn on?

 

I do have a multimeter but I barely know how to use it! How would I go about testing the buckles?

I'd like to think if there was something else causing an issue (like a retractor issue) then that would cause the light to go on instead of preventing it from lighting up.

 

Your multimeter should have a resistance/Ohm/Ω setting. The circuit in the receiver should read either low (nearly 0; closed circuit) or high (infinity; open circuit) resistance depending on whether the buckle is inserted. Since the light goes on when you bridge the cab-side plug, I'd expect infinite resistance when buckled and low resistance when unbuckled.

You could also use a simple test light and DC power source for a test like this. Light on = closed circuit, light off = open circuit.

 

If you can jump the terminals and it works but it doesn't work with the buckle switch it can't really be anything but a bad switch or a terminal fitment issue in the connector.

 

ok, that makes sense. I did actually try that but without knowing what I was looking for or expecting it to be, it was kind of pointless. thank you!

Thank you. really does point towards the buckle since the connector is nice, clean and solid.

 

alright, multimeter results on the buckle receptacle - buckled or unbuckled - it showed 1. I assume this is the high reading right?


I pulled apart the spare buckle.The white bracket slider thingy slides up and down on the brown board. When the slider is ABOVE the bottom white line, we have a reading of like 4.5 ohms. When the slider is BELOW the bottom white line, it gives the 1 reading. I put the slider above the white line, plugged it into plug in the truck and BAM the light came on like it's supposed to! Put the male part of the seat belt into the receptacle and BAM the light goes off like it's supposed to. Problem is when it's unbuckled, the light stays off. The slider doesn't return to an above line position. The buckle switch is obviously the problem. How to fix it though? I don't see anything to help the slider return to it's original position. I made sure to keep an eye out for any springs or anything when I opened the buckle housing so I'm stuck. I've played around with the position of the slider, the buckle and the button and the slider function won't return to normal.

Kinda thinking I may have to settle for the light not working properly since the buckles are NLA and buying used is going to be a crap shoot.

 

if u place a 'loop' on the pigtail that runs under the carpet(like a paper clip or wire)
does this change the light as far as going on or off?

 

Doing that causes the light to flash

 

A firm^^^^

what about that seat belt rebuild vendor?