2nd Gen Non-Engine/Transmission What does your seat belt light do?

[Renoram]

As you can see from my bio I have a '99 quad cab. Here's what I hope you all can help me with. My red seat belt light on the dash comes on & goes off when you turn the key on (I guess they call it a bulb check) OK. But it never comes on after that when you open either doors. I also don't get any kind of buzzer warning. Can you tell me what your truck does?



Also, a second problem I think I have that is related to this is both passenger & driver seat belt inertia reels lock up almost exactly at 30 minutes after I turn the key on & am going down the road & the seat belt light comes on (at that same time). It will only reset if the key is completely removed from the ignition. I have changed 2 seat belt modules (under & between the front seats) & 1 body computer (behind the dash ash tray) already, with no help.



I think I have 2 problems or 1 problem related to each other. Can you help me solve this problem? Any comments & advice will greatly be appreciated.



Thanks ahead,

chet

 

[DBurroughs]

I was looking for simalar info when I was wiring my seat belt module. I was able to browse through a 99 factory service manual at the dealership at it had a lot of info on the operation and trouble shooting of the seat belt module. I would start by trying to get ahold of the FSM. One of the functions of the seat belt module is that it is a timer, a thirty minute timer to be exact, thirty minutes after the ignition is off and the door is open and closed, seatbelt module cuts power to the seat belt solenoid to prevent drain on the battery and the belts lock. They unlock again when the door is opened. I dont remember all the specifics of the lock and unlock cycles but I would also look at your door switches.

 

[Renoram]

One of the functions of the seat belt module is that it is a timer, a thirty minute timer to be exact, thirty minutes after the ignition is off and the door is open and closed, seatbelt module cuts power to the seat belt solenoid to prevent drain on the battery and the belts lock. They unlock again when the door is opened.

Thanks for the reply. Your reply helps a lot to understanding this system. As I mentioned, I have already changed 2 seat belt modules already, with no help. The puzzling thing is that when the key is out, the seat belt inertia solenoid does not lock out either belt as you mention. I will check the 2 door switches next. Are they in the front door jam?



I presume you have a '99. Can you tell me if you get a chime & red dash warning light when either door is opened? Mine doesn't.

 

[MLeppen]

Renoram



I have a 99 and it doesn't chime or light when door is opened, while running.

And have noticed the light will some times come on for awhile and stay on for maybe 10- 20 minutes and other times no light. Seldom use belt though.

 

[JHudson]

Wow, I thought I was the only one who fought this problem! Anyway after replacing 2 seatbelt timers and one week of dealer work, which they didn't solve I found what my problem was..... RFI from an Alpine XM radio which I installed. I used all the nice wire adapters that would hook right up to the existing factory wiring so it was a easy install, all of 30 minutes. This was back in April of 2005.



I made my first trip on Memorial weekend pulling my fiver and I though to myself after getting in the truck to buckle my seatbelt I could not pull it out and the only way it would release was to turn the ignition key to the on position. I remembered that I never had to do this before. I also noticed that after 30 minutes, opening the doors, the seat belts would not unlock.



When I got home, I went to the service manual and everything pointed to the seat belt timing module, so I replaced it and guess what... didn't change a thing. Went back to the manual and read more that the seat belt timer also works with the central timing module, under dash, and also works with the door switches. Everything that I could check didn't cure the problem, so off to the dealer.



At the dealer, scan tool and read codes, and scanner said a seatbelt timer problem and the dealer replaced it. I told them I had already done that and they responded that the scanner says it is bad. Well I knew better and sure enough when I got home after 30 minutes upon opening the door I could buckle my seat belt.



I called the dealer back and they had me bring it back and they worked on it for a week calling Chrysler for help. I spoke directly to the mechanic, and he was completely puzzled. He replaced the seat belt timer again and checked for bad grounds and replaced both door switches without resolving the problem. They didn't charge me for anymore parts or time on the truck, and just said, sorry, don't know what is wrong.



Well, I brought the truck home and started to think more on this problem and said to myself, when did the problem start? ..... after the installation of the new XM radio. With this thought in mind, I got in the truck without turning on the key to release the seatbelts and removed the radio. . and guess what upon disconnecting the power wire from the radio, I heard the seat belts release. With the radio disconnected everything was fine, with it connected, back to the problem.



I next called Chip at Blue chip Diesel and spoke to him about my problem and he call it RFI (radio frequency interference). He gave me a iron ring to wrap the positive and negative wire to the radio. Well the positive supplied radio wire was not long enough but the negative was so I ran another positive fused wire to the radio fuse box and guess what..... Problem fixed seat belts work as they should. Thanks Chip!!!! RFI was interfering with the CTM under the dash, go figure that one.



Sorry about the long reply. I hope this helps you out as it was a hard one to figure. Also talking to the dealer, this seat belt system was used on 2 years only. Not sure if 98 or 2000, but I know it is in the 99.

 

[Renoram]

MLeppen- thanks for your reply. I need to find out what is supposed to be standard so I know what mine should do.



JHudson-

Thank you too, for your reply at length. Thats what I need, as much detail from as many resources. I am familiar with RF as I work on airline jet aircraft for a living & we have radar, radio, navigation & many other electronics that have shielded wires to contain &/or keep out stray inductance but I don't have any new radios or electronics that I have installed since I noticed the problem (I actually have had this problem for over a year & have been procrastinating, but now I want to get it done!). I once had a CD changer, but that crapped out a long time ago & I ripped it out & never replaced it. I did have a remote start unit/power door lock system installed by Best Buy in '99, but the Dealer removed it after it blew 2 ECMS under warranty. They installed a 3rd one & told me if I put it back in they would not pay for another one under warranty- something like $1500. It hasn't had that kind of problem since then. As you can see from my original posting that my problem is a little different from yours, but I know what you're saying - anything can go wrong with stray RF. I would appreciate it if you can you tell me how your door chime & red dash seat belt light work when you open the doors with the key in ignition & turned on. Today it's snowing, but it's supposed to clear up in the next day or so. at that point I am going to check my door jam switches, although my dome light comes on when I open the door. I've got to be closing in on this- or I'll have to bypass 12vdc power around the seat belt module to the seat solenoids!

 

[JHudson]

Hi,





I just went out and check my function of the seat belt light and chime. Mine works just like yours. Turn the key on and the seat belt light blinks and chime will sound if the seat belt is not fastened. No chime if belt is fastened. You can open the door no light or chime, and ditto on the belt when unfastened.



So the answer to your first question is the light and chime are operating normal.



I just remembered that you can put the seat belt timer into test mode. Here is how. . from the 99 service manual

1) Sit in the driver side front seat

2) Push in the cigar lighter (I found that this is unnecessary as long as you run the cycles within 5 seconds)

3) Within five seconds the ignition switch must be cycled on, off, on, off, on, off and then finally back to on. Leave the ignition switch in the on position for the remainder of this procedure. This action enter the seat belt control system into its test mode for a maximum of five minutes. After five minutes the seat belt control system will automatically return to its normal operating mode.

4) The seat belt reminder lamp should light shorty after entering the test mode to confirm that the seat belt control system is in the test mode, and that the seat belt control system fault circuit is functional. If the lamp fails to light, use a DRB scan tool and the proper diagnostic procedures manual to diagnose the SCTM fault circuit to the ACM, the ACM, and the CCD data bus.



Once you are in this mode, you will here the solenoids release thereby locking the retractors. If you open the drivers door, the left solenoid will power up releasing the seat belt. The right side works the same way.



Just a side note, you have to cycle to key fast as it will not go into this test mode. Also the light takes about 10 seconds to go on indicating test mode.



Lastly, if there are any codes, the scan tool will find them in the Airbag control module.



As you can see, the seat belt system is much too complicated. I can see why it was used only in two model years of trucks. Unfortunately it looks like we got stuck with a tough system.



Good luck

 

[foolkiller]

it's funny that every issue that i have with my beasty is either already posted or gets posted soon after i see it.



i have yet to actually help anyone here... . but you all help me ... so here goes.



my seat belt light issues were solved by finding every harness plug i could find that had anything to do with the seatbelts and simply



unplug



look them over



shoot a little electrical contact cleaner in the if nessesary



and plug them back in



everything works great since... good luck.



jeff

 

[Renoram]

I was looking for similiar info when I was wiring my seat belt module. I was able to browse through a 99 factory service manual at the dealership at it had a lot of info on the operation and trouble shooting of the seat belt module. I would start by trying to get ahold of the FSM. One of the functions of the seat belt module is that it is a timer, a thirty minute timer to be exact, thirty minutes after the ignition is off and the door is open and closed, seatbelt module cuts power to the seat belt solenoid to prevent drain on the battery and the belts lock. They unlock again when the door is opened. I dont remember all the specifics of the lock and unlock cycles but I would also look at your door switches.

Today I proved out what your post says & it works as advertised. After 30 minutes of removing the key & closing the driver door, the seat belts locked out. I opened the driver door & pulled on the shoulder harness & the seat belt was released. Thats telling me that the system is halfway working- the door switch anyway. Now to find out why the module starts to time out as soon as the key is turned on with the door closed driving down the road. I'd like to see the innards schematic or block diagram of the seat belt module to see what the inputs to the timer are. Where do you think I could find that?



I didn't have time to do the self test JHudson posted. Try & get to it tomorrow.



Any more ideas, please postum.

 

[DBurroughs]

I have a 97, but bought 99 seats on Ebay, unknowingly they had this whole seat belt timer system, so that's why I am figuring this out. I wired mine up last friday and took a 500 mi round trip and the seat belts seem to work fine. I posted the wiring diagram for the seatbelt module in the other thread but here it is again.



DB 18 (dark blue, 18 ga)-fused ignition power in Run and Acc

PK 18-fused battery power

LG/BK 18 (light green/black)-airbag contol module, this is the fault signal from the seatbelt control module that would light the airbag light in the dash if the seatbelt control module is faulty

OR/BK 18-to left seatbelt solenoid

OR/RD 18-to right seatbelt solenoid

TN (tan) 18 to left door ajar switch

TN/RD 18 to right door ajar switch

BK/LG 18 Ground

LB/PK 18 Ground



There will also be a selt belt switch for the seat belt light in the dash, it is a LG/RD 18 wire that grounds when the seat belt is out.

 

[Renoram]

I have a 97, but bought 99 seats on Ebay, unknowingly they had this whole seat belt timer system, so that's why I am figuring this out. I wired mine up last friday and took a 500 mi round trip and the seat belts seem to work fine. I posted the wiring diagram for the seatbelt module in the other thread but here it is again.



DB 18 (dark blue, 18 ga)-fused ignition power in Run and Acc

PK 18-fused battery power

LG/BK 18 (light green/black)-airbag contol module, this is the fault signal from the seatbelt control module that would light the airbag light in the dash if the seatbelt control module is faulty

OR/BK 18-to left seatbelt solenoid

OR/RD 18-to right seatbelt solenoid

TN (tan) 18 to left door ajar switch

TN/RD 18 to right door ajar switch

BK/LG 18 Ground

LB/PK 18 Ground



There will also be a selt belt switch for the seat belt light in the dash, it is a LG/RD 18 wire that grounds when the seat belt is out.

Thanks a million for taking the time to repost the wires to the SB module. I really appreciate it & did actually see it in your other post. I understand what is happening going to the module now, but now what I really need is whats going around inside the module to make the timer initiate when I'm going down the road- like drivers, resistors, diodes, and gates, or gates, timer & whatever else may be in there & how they all work together. I think what I ultimately need to find is what's starting that timer going on (when it shouldn't) when I turn the key on & head on down the road.

 

[Renoram]

it's funny that every issue that i have with my beasty is either already posted or gets posted soon after i see it.



i have yet to actually help anyone here... . but you all help me ... so here goes.



my seat belt light issues were solved by finding every harness plug i could find that had anything to do with the seatbelts and simply



unplug



look them over



shoot a little electrical contact cleaner in the if nessesary



and plug them back in



everything works great since... good luck.



jeff

Jeff- Thanks for your reply. That was the first thing I did when I initially discovered the problem. But that was no help. chet

 

[Renoram]

Hi,





I just went out and check my function of the seat belt light and chime. Mine works just like yours. Turn the key on and the seat belt light blinks and chime will sound if the seat belt is not fastened. No chime if belt is fastened. You can open the door no light or chime, and ditto on the belt when unfastened.



So the answer to your first question is the light and chime are operating normal.



I just remembered that you can put the seat belt timer into test mode. Here is how. . from the 99 service manual

1) Sit in the driver side front seat

2) Push in the cigar lighter (I found that this is unnecessary as long as you run the cycles within 5 seconds)

3) Within five seconds the ignition switch must be cycled on, off, on, off, on, off and then finally back to on. Leave the ignition switch in the on position for the remainder of this procedure. This action enter the seat belt control system into its test mode for a maximum of five minutes. After five minutes the seat belt control system will automatically return to its normal operating mode.

4) The seat belt reminder lamp should light shorty after entering the test mode to confirm that the seat belt control system is in the test mode, and that the seat belt control system fault circuit is functional. If the lamp fails to light, use a DRB scan tool and the proper diagnostic procedures manual to diagnose the SCTM fault circuit to the ACM, the ACM, and the CCD data bus.



Once you are in this mode, you will here the solenoids release thereby locking the retractors. If you open the drivers door, the left solenoid will power up releasing the seat belt. The right side works the same way.



Just a side note, you have to cycle to key fast as it will not go into this test mode. Also the light takes about 10 seconds to go on indicating test mode.



Lastly, if there are any codes, the scan tool will find them in the Airbag control module.



As you can see, the seat belt system is much too complicated. I can see why it was used only in two model years of trucks. Unfortunately it looks like we got stuck with a tough system.



Good luck

I just did this test & it failed. The seat belt light did not ever come on except for when I initially turned key on & I did not hear any seat belt solenoids click. They remained released throughout the test period. What does DRB stand for. Is it that OBD II scanner to read & erase codes?

 

[CCutshaw]

I just did this test & it failed. The seat belt light did not ever come on except for when I initially turned key on & I did not hear any seat belt solenoids click. They remained released throughout the test period. What does DRB stand for. Is it that OBD II scanner to read & erase codes?

All Chrysler cars with OBD-II standard have a second memory in the engine control module. This memory is accessible through the Chrysler diagnostic tool DRB.

Calvin

 

[JHudson]

I just did this test & it failed. The seat belt light did not ever come on except for when I initially turned key on & I did not hear any seat belt solenoids click. They remained released throughout the test period. What does DRB stand for. Is it that OBD II scanner to read & erase codes?

The DRB is the Chrysler scan tool. It plugs into the standard OBD II port in the cab. I do know that the fault code is read in the Airbag control module and the Chrysler scan has the ability to do this.



Just a reminder, when going into test mode, do not move the key back to the "lock" position when cycling the ignition switch. Turn to on, then back to off, then to on until you are back to on for the fourth time. Keep the key on and wait about 10 seconds and the seatbelt light will come on the the seatbelts will lock. It took me a few times to get the timing right before it would enter the test mode.

 

[Renoram]

The DRB is the Chrysler scan tool. It plugs into the standard OBD II port in the cab. I do know that the fault code is read in the Airbag control module and the Chrysler scan has the ability to do this.



Just a reminder, when going into test mode, do not move the key back to the "lock" position when cycling the ignition switch. Turn to on, then back to off, then to on until you are back to on for the fourth time. Keep the key on and wait about 10 seconds and the seatbelt light will come on the the seatbelts will lock. It took me a few times to get the timing right before it would enter the test mode.

Is the DBR scan tool something I can get readily or is it a dealer only thing? If it can be had, where's the best place to buy it & how much is it?



Thanks for the extra info on the test.

 

[JHudson]

Is the DBR scan tool something I can get readily or is it a dealer only thing? If it can be had, where's the best place to buy it & how much is it?



Thanks for the extra info on the test.

The DBR scan tool is a dealer thing. I have only seen two of them. My dealer has one and Blue Chip Diesel has one. I asked Chip how he got his and he paid $5000. 00 for it and has to pay for the software updates to keep the machine current. Apparently they do not come cheap either. I am not sure if the standard OBD scan tools will read the faults in the other modules in our trucks, but maybe a trip to AutoZone will be able to answer that one.



Were you able to get into test mode and just thinking a little about your issue, is the seat belt timer loosing power when you are running down the road, thereby starting the 30 minute timer?



When I had issues with my truck I took out the drivers door switch so it would not activate the timer, so in other words, the door would appear to be shut, but allowed me to work the issue. Maybe you could do this with the truck running and wait for the seatbelts to lock and see if the ignition power feed is still hot to the seatbelt timer module. If it isn't it would give you a start on your problem.



Good luck, and let me know your progress.



Jay

 

[Renoram]

The DBR scan tool is a dealer thing. I have only seen two of them. My dealer has one and Blue Chip Diesel has one. I asked Chip how he got his and he paid $5000. 00 for it and has to pay for the software updates to keep the machine current. Apparently they do not come cheap either. I am not sure if the standard OBD scan tools will read the faults in the other modules in our trucks, but maybe a trip to AutoZone will be able to answer that one.



Were you able to get into test mode and just thinking a little about your issue, is the seat belt timer loosing power when you are running down the road, thereby starting the 30 minute timer?



When I had issues with my truck I took out the drivers door switch so it would not activate the timer, so in other words, the door would appear to be shut, but allowed me to work the issue. Maybe you could do this with the truck running and wait for the seatbelts to lock and see if the ignition power feed is still hot to the seatbelt timer module. If it isn't it would give you a start on your problem.



Good luck, and let me know your progress.



Jay

I did not have a chance to do the test again nor the door switch troubleshooting as you did. I can tell you that the seat belt timer starts timing out as soon as I turn on the ignition. I got diverted yesterday & had to go to Roseville, CA (about 120 miles- just before Sacramento- 1 3/4hours) to see my daughter & grandson. Also I installed an Edge Comp. The weather was good so we hooked up our 21' Cherokee travel trailer & headed down the road. We camped for 1 night @ Folsom lake. I just got back. But to get to the point, what I did do to be able to release the seatbelt/shoulder harness, was to rig a test lead from the power port to both seat belt solenoids. I had a power port plug laying around with 3' of wire attached. I used an inline splice to each power wire of the solenoids @ the seat belt module plugs, & then spliced them together to the port plug wire. When the seat belt warning light came on & the belts locked up 30 minutes down the road, I plugged in the power port plug. The seat belts released, but the warning light remained on until I removed the key down the road. The main object was to release the seat belt to make it comfortable for the wife & I. At least I know the induced 12vdc will release the solenoids. Also FYI, when I was splicing into the solenoid wiring at the seat belt module, I notice that there was 3 wires on the driver side as opposed to 2 on the passenger side. The color code matched up except for the 3rd wire. I dont remember the color but will check tomorrow. I will let you know as things happen. The saga continues!



By the way, the Edge comp worked great up & down the hill- 8000'. I ran it at level 1-3. I did not stab the pump wire.

 

[CCutshaw]

The in the dash light is not working on my truck I think it’s a bad switch were the seatbelt hooks.



In your case the timer has two 12volt connections. One is for the computer on all the time, the second is switched. After reading my shop manual last night I wonder if your problem is that the timer is ether losing 12volts after you start the truck or it’s never there. When you open the driver’s door the seatbelt latches energize, after 30 minutes they turn off if the truck is not running. Good luck

Calvin

 

[Renoram]

The in the dash light is not working on my truck I think it’s a bad switch were the seatbelt hooks.



In your case the timer has two 12volt connections. One is for the computer on all the time, the second is switched. After reading my shop manual last night I wonder if your problem is that the timer is ether losing 12volts after you start the truck or it’s never there. When you open the driver’s door the seatbelt latches energize, after 30 minutes they turn off if the truck is not running. Good luck

Calvin

Calvin- You hit it on the head! After assuming the fuses were good I was troubleshooting everything downline. You know what they say about assuming. So, I doubled back after reading your post & checked the hot wire & the ignition wire. I did not have it when I turned the ignition on. I went to the fuse & low & behold, the fuse was blown! While I am not 100% sure this the fix, I would guess it's 99%- thats what I call a hard fail. I did not have time to make a 30 minute drive after changing the fuse. I will take the drive tomorrow to confirm.



While it took this long hunting, I learned a great deal about the idiosyncrasies of this system due to all the great inputs from everyone. THANK YOU EVERYONE- I couldn't have done it without you. But I would sure like to strangle the engineer who designed this. He had way too much time on his hands to come up with this system! chet



Calvin- regarding your problem, does your seat belt warning light come on when you first turn on the key? If it doesn't, yur bulb in the dash is bad. I was looking at the wiring diagram & it shows the input to the light coming from the seat belt module. My truck does not have wiring going to the buckle, so like some said, you will not get the seat belt light after the initial start when you turn the key on. Mine doesn't, but my buddys 2001 does & he has wiring to his buckles. Hope that helps- I always like to pay back a good deed.