Aftermarket Seat Install - Passenger Seatbelt

[CrazedAntelope]

Hi All,

I attempting to chase down my airbag light after installing driver and passenger Sparco seats in my 2015 mustang. I think I've successfully tricked everything except for in the passenger seatbelt area.

It is stating "circuit open" on the passenger seatbelt tension sensor, which I suspect it is triggering the RCM to throw the airbag lamp on. I noticed the driver's side seatbelt only has 2 wires, whereas the passenger side's seatbelt has 5.

Does anybody know what the electronics in passenger seatbelt is doing? I'm trying to get an account setup with MotorcraftService.com but I'm having some issues getting the wiring diagram.

Wondering if anybody here as an idea of what could be going on with the passenger seatbelt and if anybody's had this issue with aftermarket seats. A wiring diagram would helpful as well.


The current codes (read by FORScan) are:

• Module: Occupant Classification System Module
  • Code: B0061 - Passenger Seatbelt Tension Sensor
  • Additional Fault Symptom (:13):
    - Circuit Open
  • Status (-2B):
    - TC Present at Time of Request
    - Malfunction Indicator Lamp is Off for this DTC
• Module: Restraint Control Module
  • Code: B00AO - Occupant Classification System
  • Additional Fault Symptom (:68):
    - Event Information
  • Status (-8B):
    - DTC Present at Time of Request
    - Malfunction Indicator Lamp is On for this DTC

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[CrazedAntelope]

Update:

So I ended up obtaining a Ford Service Manual and I followed some of the troubleshooting steps. All troubleshooting routes pointed to me needing a new passenger seatbelt buckle. Instead of paying ~$180 for a new one and waiting for it to be shipped, I ended up finding a way to trick the OCSM (Occupant Classification System Module) and RCM (Restraints Control Module) as well.

On my original post the OCSM was circuit open. The Ford manual asked me to bridge pins 1 and 3 on C3238 and re-test the OCSM. It then read with code :11 (Short to Ground).

I basically just proceeded to bridge pins 1 and 3 with varying resistances, until It was neither reporting "open" or "short to ground". All the while, I put a 2.2ohm 1W resistor between pin 1 and 2, to simulate some sort of tension on the belt. The belt tension uses a hall-effect sensor that modifies a voltage between the vref and vsignal on the OSCM.

I was able to cut off the passenger safety belt buckle, as I am using Schroth 4 point ASM harnesses with the DOT legal buckles instead.

ABSOLUTELY DO NOT DO THIS IF YOU ARE USING OEM SEATBELTS AND HARNESSES. I WILL NOT BE LIABLE FOR ANY DEATH, INJURY, OR DAMAGES DUE TO YOUR FAULTY REPAIR.

I wish I could summarize what resistance is bridging between pins 1 and 3 with confidence, but my multimeter is not accurate. Theoretically, it should be 5.46k ohm (4.7k + 500 + 220 + 20 + 20), but my mulitmeter was reading more like 5.3k.

After doing my modifications to pins 1, 2, and 3, the OCSM was happy but the RCM throwing a code related to the lack of seatbelt on pins 5 & 6. I found a 1k ohm resistor between 5&6 suffices to make the RCM happy.

I believe the 1k ohm resistor reports the belt as unbuckled, judging by the behavior my car is displaying on the Passenger Airbag Deactivation (PAD) Indicator light when putting no weight, light weight, and heavy weight in the front passenger seat.

Even though it is unbuckled, the presence of the passenger airbag illumination when putting 20lbs on the front seat indicates the OCSM is checking for passenger weight. The absence of the passenger airbag light when sitting in the seat indicates that the OCSM has detected a large occupant, and whether buckeld or unbuckled, the airbag status should be "enabled".

In summary, I was finally able to fix the airbag light on my car. Not sure why the passenger buckle went bad while I'm also installing aftermarket seats, maybe God is testing my troubleshooting skills. This is not all that is needed to defeat the lights when installing aftermarket seats.

If you are a DIYer trying to turn off your airbag light, I highly recommend getting your hands on service manual and having access to Forscan. I subscribed to Solera Direct-Hit Identifix for the manual, which cost me $20 for 1 month. I used a OBD2 to USB adapter with HS/MS functionality to plug into a windows laptop running Forscan for the diagnostincs.

If you do decide to work on your airbags yourself, please remember to be extra careful. And remember, I am not liable.

 

[luc]

Using a 4 pts harness is a very bad idea
Beside the submarine issue, yes even with the schroth, as you tighten the shoulders belts, the lap belts are going up
Just do it correctly and use a 5 or 6pts
And frankly your liability disclaimer seems a little strange with you putting a passenger at risk with a 4 pts
Shit happens on a race track

 

[CrazedAntelope]

The harnesses I am using are the 4 point Schroth with anti-submarining via the shoulder belt that is stitched to extend in the event of a crash. As far as I know it is the only aftermarket harness that is street legal.

 

[luc]

The harnesses I am using are the 4 point Schroth with anti-submarining via the shoulder belt that is stitched to extend in the event of a crash. As far as I know it is the only aftermarket harness that is street legal.

I know which harness you are talking about. I use it. Driver side with a 5 pts in my car
How do you deal with the lap belts going up as you tighten the shoulders belts ???
Do you mean that the car is not going to be taken to the track?
If so why putting a racing seat and harness? Make no sense except i guess for look
So basically you get the worst of both worlds, a ineffective airbag and a ineffective racing harness

 

[CrazedAntelope]

I know which harness you are talking about. I use it. Driver side with a 5 pts in my car
How do you deal with the lap belts going up as you tighten the shoulders belts ???
Do you mean that the car is not going to be taken to the track?
If so why putting a racing seat and harness? Make no sense except i guess for look
So basically you get the worst of both worlds, a ineffective airbag and a ineffective racing harness

Yeah this post wasn’t to discuss the merits of 4 point vs 6 point harnesses. It was for a technical issue and I updated it with a technical solution.

Also, Schroth sells a 5th and 6th point addon that fits into the DOT legal buckle.
Sounds like you’re not too interested in having kids with your 5 point harness, and with your attitude that sounds like a good call.

 

[luc]

Yeah this post wasn’t to discuss the merits of 4 point vs 6 point harnesses. It was for a technical issue and I updated it with a technical solution.

Also, Schroth sells a 5th and 6th point addon that fits into the DOT legal buckle.
Sounds like you’re not too interested in having kids with your 5 point harness, and with your attitude that sounds like a good call.

What I’m trying to explain to you is that a 4 pts is not the safest for either track or street
For street, the factory 3 pts is designed to work with the airbag and for the track you need 5/6 pts
Nothing more

 

[slowdown]

I just think people are chiming in based on experience and safety. You wouldn't pass tech in my HPDE club with 4pt - it's either 3 pt and airbags or 5/6 pt with HANS (with or without bags)

I've replaced both seats, 6pt harnesses, and have an airbag light. Doesn't bother me in the slightest.

But I do think it's good that you shared this for anyone bothered by the light that wants to disable.

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