Member Since: 06 Apr 2021
Location: Virginia
Posts: 19
Front Impact Sensors
I'm struggling to decide what to do with my LR3 after hitting a deer. I've got the bumper off and I just want to make sure the impact sensors are good at this point. The two sensors are identical and only have two pins each. I tested resistance across the pins and got 1.3 mega ohms for both sensors. Does that sound right?
21st Feb 2023 5:48 am
Flapper
Member Since: 04 Feb 2015
Location: Gloucester
Posts: 329
Did your airbags deploy?
21st Feb 2023 9:57 am
Sidestick
Member Since: 22 Apr 2012
Location: Rome
Posts: 2288
Front impact sensor just trigger the restraint control module so they should be good, what to check is the RCM using a dedicated diagnose tool.
In any case if you don't have the SRS check light on, inside instrument panel, the system should be still efficient.
Each impact sensor incorporates an accelerometer and a microcontroller powered by a feed from the RCM (restraints control module) . The power feed also provides the interface connection through which the impact sensor communicates with the RCM (restraints control module) using serial data messages. Acceleration is evaluated by the microcontroller and transmitted to the RCM (restraints control module) , which then makes the decision on whether or not to activate the air bags and pretensioners.
The RCM (restraints control module) is installed on the top of the transmission tunnel, in line with the B pillars, and controls operation of the SRS. The main functions of the RCM (restraints control module) include:
� Crash detection and recording.
� Air bag and pretensioner firing.
� Self test and system monitoring, with status indication via the SRS (supplemental restraint system) warning lamp
and non volatile storage of fault information.
A safing sensor in the RCM (restraints control module) provides confirmation of an impact to verify if air bag and pretensioner activation is necessary. A roll-over sensor monitors the lateral attitude of the vehicle. Various firing strategies are employed by the RCM (restraints control module) to ensure that during an accident only the appropriate air bags and pretensioners are fired. The firing strategy used also depends on the inputs from the safety belt switches and the occupant monitoring system.
An energy reserve in the RCM (restraints control module) ensures there is always a minimum of 150 milliseconds of stored energy available if the power supply from the ignition switch is disrupted during a crash. The stored energy is sufficient to produce firing signals for the driver air bag, the passenger air bag and the safety belt pretensioners.
When the ignition is switched on the RCM (restraints control module) performs a self test and then performs cyclical monitoring of the system. If a fault is detected the RCM (restraints control module) stores a related fault code and illuminates the SRS (supplemental restraint system) warning indicator. The faults can be retrieved by T4 on a dedicated link between the RCM (restraints control module) and the diagnostic socket. If a fault that could cause a false fire signal is detected, the RCM (restraints control module) disables the respective firing circuit, and keeps it disabled during a crash event.- Easy-Lift suspension module 4.0
- GoodWinch 9500 lb
- Full underbody protections
- Tree/Rock sidebars
- Prospeed roofrack & ladder
- Compressor guard
- Raised Air Intake
- Driving lights (2+4)
- 50 mm Waffle boards
- Altox Heater control
- Overland Rooftop Tent
- Rear seats entertainment
- Front & Rear camera
- GVIF
- Removable tow bar
- Cubby box fridge
- BFG KO2 265/65R17
- iidTool BT
21st Feb 2023 10:22 am
aaronb1013
Member Since: 06 Apr 2021
Location: Virginia
Posts: 19
Many thanks for the helpful response. Looks like I buried the lede. The front driver-side airbag did deploy as did the seatbelt tensioner for the driver seat. I sent the SRS RCM to myairbags.com to reset it but they claimed that communication to the module was impossible. I find that funny because the fuel pump won’t run if the module isn’t plugged in but the car runs fine when I plug it in. Sounds like I can reset everything with an IID tool. This is a 2008 LR3 SE, BTW.
I think I’m just going to assume impact sensors are fine and move on to the module. (Already replaced seatbelt) The bumper cover is no trouble to take on and off BTW. I might try and replace with a steel bumper sometime. I’ve already put so much fun stuff into this LR3 it’s going to be tough to scrap it. Glad to know others have been down this path.
21st Feb 2023 3:31 pm
aaronb1013
Member Since: 06 Apr 2021
Location: Virginia
Posts: 19
Actually, I just googled T4. That is not the same as an IID tool. I’lol need to find a dealer I guess. I have little trust in what Myairbags.com did.
21st Feb 2023 3:35 pm
aaronb1013
Member Since: 06 Apr 2021
Location: Virginia
Posts: 19
Update for future interested parties: The airbag deployment codes were easily cleared by my dad's Autel scanner. One pesky code remains B12121-B. Apparently there's a wiring problem with the seatbelt pretensioner. This is the one things myairbags.com claimed to fix. So now it's looking like sending anything to them was a complete waste of money. Anyways, I'll update once I figure the last piece out.
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