Seatbelt light always on - suggestions?

[Sobek]

Originally Posted by amlav

Got the feeling that the seat belt light is controlled by the PCM .
Just wandering if you short the 2 pins and the light and buzzer comes on
would they go off after few seconds or after you turned ignition on ??

I'll actually give this a try, not a bad idea! I know that my PCM is a bit funny, it no longer turns on the aux fan automatically when temps reach the threshold... this may be yet another symptom of it slowly dying on me.

Originally Posted by layback40

Have you tried plugging the seatbelts in with no one on the seats to see if that fixes it. I suspect there are weight sensors in the passenger's seat, that maybe stuck.

No weight sensors on my XJ! This is a totally factory barebones 95 sport, didn't come with seatbelt sensors, weight sensors... nothing at all, really. We didn't get much for our $45k

Originally Posted by Jonny Jeep

Seat belt light is operated by that unit and even though an eight pin module is shown in the fsm it looks like only six pins are used anyway. The seat belt input is from the buckle.

If the module is plugged in and the connector to the drivers seat belt buckle is unplugged, when the ignition is turned on if the light goes out after 4-8 seconds but comes back on when the seat belt buckle is reconnected, then the switch inside the buckle is stuck on.

If the light doesn't go out the timer or contacts in the unit are stuck on.

Given that this Heep never came with any buckle sensors or anything (just the one buzzer connector over on the passenger side, unused from factory), the possibility of a timer / contact issue with the chime module seems the most likely culprit. Do you have any idea of the timing function of the light is controlled within the chime module, or by the PCM? Hmm! I now have replacement front seats from a later XJ that have buckle sensors, but as I only have the one connector on my factory harness, it's a little odd. But I will definitely play around with it some more and see what kind of behavior I can uncover along the way!

[Jonny Jeep]

I would assume the buckle switch should only be in the drivers buckle. If there was one on the passenger side you'd need to keep that belt fastened any time you didn't have a passenger in the front.

This is the info given in the 95 XJ/YJ FSM.

SEAT BELT REMINDER LAMP
The seat belt reminder lamp lights for 4 to 8 seconds after the ignition switch is turned to the ON position. A timer in the chime/buzzer module controls
ignition-switched battery feed to the lamp.

BUZZER MODULE
The buzzer module is located in the fuseblock module under the left end of the instrument panel. It receives battery voltage at all times from (fuse 15 - XJ,
fuse 3 - YJ) the fuseblock module. It also receives a
second battery feed (fuse 17 - XJ, fuse 9 - YJ) when
the ignition switch is in the ON or START position.
Other inputs to the module include the driver’s door
jamb switch, the driver’s seat belt switch, the ignition
key-in switch, and the headlamp switch (XJ only). The
only output of the module is a timed 4 to 8 second feed
to the seat belt reminder lamp in the message center of
the instrument cluster. The timer function begins after
the ignition switch is turned to the ON position.
The buzzer module can not be repaired. If faulty, it
must be replaced.

[amlav]

Looking back on to your pictures can't see any electronic component that would be similar to a timer circuit . But...what i can see is a sort of bimetal blades that have some wire windings around . Just wondering if the way it is achieving the timing is by getting voltage in to those windings and that would cause the bimetal to heat up and bend/distort and close or open some contact at the end of the bimetal blades . It would take some time for the generated heat to bend the bimetal and that would be the actual timing . Just a tought .....

[Sobek]

Originally Posted by Jonny Jeep

I would assume the buckle switch should only be in the drivers buckle. If there was one on the passenger side you'd need to keep that belt fastened any time you didn't have a passenger in the front.

This is the info given in the 95 XJ/YJ FSM.

SEAT BELT REMINDER LAMP
The seat belt reminder lamp lights for 4 to 8 seconds after the ignition switch is turned to the ON position. A timer in the chime/buzzer module controls
ignition-switched battery feed to the lamp.

BUZZER MODULE
The buzzer module is located in the fuseblock module under the left end of the instrument panel. It receives battery voltage at all times from (fuse 15 - XJ,
fuse 3 - YJ) the fuseblock module. It also receives a
second battery feed (fuse 17 - XJ, fuse 9 - YJ) when
the ignition switch is in the ON or START position.
Other inputs to the module include the driver’s door
jamb switch, the driver’s seat belt switch, the ignition
key-in switch, and the headlamp switch (XJ only). The
only output of the module is a timed 4 to 8 second feed
to the seat belt reminder lamp in the message center of
the instrument cluster. The timer function begins after
the ignition switch is turned to the ON position.
The buzzer module can not be repaired. If faulty, it
must be replaced.

https://www.ausjeepoffroad.com/forum...5127b143da.gif

Awesome, thank you for that information! I see what you mean now, those two additional pins seem to be either redundant for other models, or possibly additional ground points on later XJ's perhaps.

Originally Posted by amlav

Looking back on to your pictures can't see any electronic component that would be similar to a timer circuit . But...what i can see is a sort of bimetal blades that have some wire windings around . Just wondering if the way it is achieving the timing is by getting voltage in to those windings and that would cause the bimetal to heat up and bend/distort and close or open some contact at the end of the bimetal blades . It would take some time for the generated heat to bend the bimetal and that would be the actual timing . Just a tought .....

I had a good look inside again and you're absolutely right, they are both flexible bi-metal strips! It's actually a pretty good design, and would last well beyond the expected service life of the vehicle back when they designed it (not accounting for its popularity and people's determination to hit a million kilometers in them ). The actual strips are still good, no breaks / deformation, so I suspect either the windings have failed and it's no longer able to heat up the strip (there IS some disclouration on top of the windings that could be from overheating/burnout deeper within the winding mass) or the actual INPUT power to the windings from the ignition switch has failed in some fashion. I have a funny feeling it might actually be the ignition starter switch... from what I can glean online, it's sending it's power signals out via conductive trace contacts, and I bet you anything that whatever one runs to the chime module for the seat belt lamp has worn down, burnt out, broken, or become too dirty to conduct, so the windings never heat and the bi-metal strips never separate. I wish I could find a picture of a disassembled ignition starter switch, but it looks like no one ever really bothered to open one up and share it with the world. Bugger.

I know this is all kind of nonsense talk for most XJ owners about a stupid seat belt light, but I like knowing how things work and IF possible, how to repair them. I suppose the only way to know for sure would be to either replace my ignition starter switch, or open mine up and check for continuity / damage. I don't feel like opening mine up, at least not without a replacement on hand, so I might buy a spare since they're cheap. But in the mean time, I'm also going to probe for voltage to the windings with the ignition on, and see if I can pin down the failure to either the chime module side, or the ignition starter switch side Curious to find out.

Thanks for the input guys, it's great to see.

By the way, where does one buy replacement seat belts from these days?? My drivers seat belt is absolutely dead after 320k kms and I doubt it will save me in a crash, plus I have to rotate it before clipping it in or the worn material RUINS cotton shirts

[awg]

Originally Posted by Sobek

By the way, where does one buy replacement seat belts from these days?? My drivers seat belt is absolutely dead after 320k kms and I doubt it will save me in a crash, plus I have to rotate it before clipping it in or the worn material RUINS cotton shirts

eBay advertise "Universal" seatbelts to fit XJ, they are only $35

They may not be exact, I have one for another vehicle, so will check how close it is

seatbelt is a rego fail if frayed or dysfunctional