Ram Promaster Forum banner

1 - 18 of 18 Posts

·
Registered
Joined
·
77 Posts
Discussion Starter #1
I'm not going to get into the discussion of whether this is a good idea or not. I wear my seat belt religiously but I start the car and then put on my belt. Always have, always will. The promaster beeps at me doing this so I looked to disable it. The sensor is buried deep in the buckle receptacle which is glued together. Not wanting to destroy my new working one to investigate I went looking for a blown buckle/pretensioner assembly. @HikerSteve came to my rescue and sent me one with the promise I'll report my findings. I took the receptacle apart to find a Cherry brand magnetic switch. The style and part number don't cross to anything I can find so I just had to figure out how it worked from probing while running.

I drug a scope out to the van and probed the voltage on the lines.
tek00001_pulse_timing_640.png


Ok, now we are getting somewhere! The van's ecu is pulsing the sensor with 5V for about 1ms at a 20Hz rate.
So I then zoomed in on one pulse and hooked a current sensor up (no buckle)...
tek00002_no_buckle_r640.png


and with a buckle inserted...
tek00003_buckle_r640.png


Doing some back of the envelope math it looks to be drawing about 12mA when the buckle is inserted. 5V/12mA=460ohm. The current at the leading edge is likely the capacitance of the circuitry in the sensor charging. Again, dirty math says 15mA*30us/5V=90nF. Not sure if its necessary to duplicate that but I'm an EE and have parts on hand in the lab. So I cut off the old sensor, soldered a 475ohm resistor and 82nF cap to the cable, and voila... no beeping when I insert the key.

Since it worked first try, I didn't drag the scope back out there to verify the new waveforms (plus its raining and I don't want to get the office's equipment wet.) Anyway, a small win today. Thanks @HikerSteve!!!
 

·
Registered
Joined
·
80 Posts

·
Registered
Joined
·
29 Posts

·
Registered
Joined
·
2,592 Posts
IIRC, I could have sworn that someone posted they put a magnetic on the buckle to get rid of the beep.
 

·
Registered
Joined
·
698 Posts
A reading from the Book of Promaster: (Mopar Tech Authority Service Manual)

The driver side seat belt switch for this vehicle is actually a Hall Effect-type sensor. This sensor consists of a fixed-position, Hall Effect Integrated Circuit (IC) chip and a small permanent magnet that is integral to the driver side seat belt buckle. The seat belt buckle is located on a molded plastic scabbard and secured by a screw to the inboard side of the upper inboard adjuster track so that the buckle travels with the seat.

The seat belt switch is connected to the vehicle electrical system through a pigtail wire and connector on the seat belt buckle-half and tensioner unit, which is connected to a wire harness connector and take out of the seat wire harness. A one kilohm diagnostic resistor is connected in parallel with the IC where the two pigtail wire leads connect to the IC pins.

The seat belt switch cannot be adjusted or repaired. If ineffective or damaged, the entire driver side seat belt buckle-half and tensioner unit must be replaced.
 

·
Registered
Joined
·
698 Posts
Now, Turning to Chapter Eight, Section J - We have instructions for the seatbelt chicken dance...

STANDARD PROCEDURE - ENHANCED SEATBELT REMINDER PROGRAMMING

The seatbelt indicator also includes a programmable enhanced seatbelt reminder or BELTMINDER feature that is enabled when the vehicle is shipped from the factory. This BELTMINDER feature provides extended and modified visual seatbelt indicator and audible chime warning responses to an unbuckled driver side front seat belt. The BELTMINDER feature may be disabled or enabled by the customer using the programming sequence that follows, or by the dealer using a diagnostic scan tool.

CUSTOMER PROGRAMMING SEQUENCE

NOTE: The following sequence of events must occur within 60 seconds of the ignition switch being placed in the ON position in order for the programming to be completed successfully.

1. With all doors closed and the ignition switch in any position except ON or START, buckle the driver side front seat belt.

2. Turn the ignition switch to the ON position and wait for the seatbelt indicator reminder function to conclude (about six seconds).

3. Unbuckle and buckle the driver side front seat belt three or more times, ending with the belt buckled.

4. Turn the ignition switch to any position except ON or START to toggle the BELTMINDER feature from its current setting (from active to inactive, or from inactive to active). A single chime tone will provide an audible confirmation that the programming sequence has been successfully completed.

(NOTE: Nothing offered for the passenger side, I wonder if this applies there too...)
 

·
Registered
Joined
·
278 Posts
So I imagine any position except ON or Start means leave the key in and in the off position? There are only three settings on my van. Off, On and Start.

Thanks for the instructions too!
 

·
Registered
Joined
·
278 Posts
My dealer said it has to be done with their computer. Said a 6 pack of beer to the tech and he will otherwise turn a blind eye! I'm sure theres a ton of liability in them doing so.

I have a Ram 2500 truck and it worked for that one. My 300c and my previous city did not take the seatbelt unbuckling trick.
 

·
Registered
Joined
·
698 Posts
It's been posted before by a known user who claimed success, I apologize on my failure to note these instructions came from a 2014 service manual, remember FCA was outed on their computers being hackable and they changed many things with reflashing the logic (one being my years rear speakers unavailable for enable w/o dealer hookup)

Anyone got a newer "RAM ProMaster Service Information Manual" CD-Rom? This info was found under Electrical, Instrument Cluster, Standard Procedure...
 

·
Registered
Joined
·
77 Posts
Discussion Starter #17
nF = nano farad. I'm not even sure the cap is needed but I have them handy so I might as well mimic the signal as best as I could.

I'm now a month or so of using this daily. No problems to report. (y)

Its a shame the PM is so annoying that it came to this. I've been driving my Ford pickup last week and noticed how much better its beeper is designed. I can start it up, get the engine warming up w/ the defrost cranked, go back out and scrape the ice, even pull it up the driveway and not one chime. It wont beep at you until you have it in drive or reverse for a short period of time while unbelted (20 seconds?). I only notice this while moving the big trailer around. A much more civil reminder implementation.
 
1 - 18 of 18 Posts
Top