4WAS Failure Statistics?

Post by **M37SJoe** » Sat Jun 05, 2021 6:19 pm

Match the wires one for one. Solder, heat shrink, tape it all up. It is not really that difficult once you cut the body harness connector. Take pictures. Jack up the back of the car for easy access. You could label each wire if you want to be certain. If this is new to you get an electrician buddy or even go to a repair shop and have them do it. Remember, a Parts Guy at an Infiniti Dealership stated that these connectors can have issues. That was what made me change the connector. The Trailer Connector is cheap and readily available. You could use something else but why? It is made for wet locations. Good luck! I changed our the Motor, the Sensor, and still had the problem. I changed out the Connector and have never had an issue since...

Post by **M37SJoe** » Sat Jun 05, 2021 6:19 pm

Match the wires one for one. Solder, heat shrink, tape it all up. It is not really that difficult once you cut the body harness connector. Take pictures. Jack up the back of the car for easy access. You could label each wire if you want to be certain. If this is new to you get an electrician buddy or even go to a repair shop and have them do it. Remember, a Parts Guy at an Infiniti Dealership stated that these connectors can have issues. That was what made me change the connector. The Trailer Connector is cheap and readily available. You could use something else but why? It is made for wet locations. Good luck! I changed our the Motor, the Sensor, and still had the problem. I changed out the Connector and have never had an issue since... What VSTAR posted is what I bought. $12.00 at Auto Zone.

Post by **dmiles140** » Sat Jun 05, 2021 7:04 pm

M37SJoe wrote: ↑
Sat Jun 05, 2021 6:19 pm
Match the wires one for one. Solder, heat shrink, tape it all up. It is not really that difficult once you cut the body harness connector. Take pictures. Jack up the back of the car for easy access. You could label each wire if you want to be certain. If this is new to you get an electrician buddy or even go to a repair shop and have them do it. Remember, a Parts Guy at an Infiniti Dealership stated that these connectors can have issues. That was what made me change the connector. The Trailer Connector is cheap and readily available. You could use something else but why? It is made for wet locations. Good luck! I changed our the Motor, the Sensor, and still had the problem. I changed out the Connector and have never had an issue since... What VSTAR posted is what I bought. $12.00 at Auto Zone.

I tried to post the pic of what I got in the previous post but it didn't work. I did get one similar to the one that VSTAR posted and cut, match and spliced together then turned the car on to see if the light came on. Before, the light would randomly come on mainly when I drove. Now it comes on as soon as I start the car. I had a c1918 code before and now I have a c1915 code instead. Any thoughts?

Post by **VStar650CL** » Sat Jun 05, 2021 7:56 pm

I think you must have got something mixed-up in the wiring. C1918 is a "glitch" code indicating a fluctuating sensor voltage, C1915 is a "dead horse" code. Since we know your sensor wasn't dead beforehand, it has to be mixed-up wires or a bad splice.

Post by **VStar650CL** » Sat Jun 05, 2021 8:20 pm

Here's the connections from the car side. You're looking at the back of the connector where the wires enter:

: B53.png (22.71 KiB) Viewed 2675 times

There's some conflicting info about the wire colors, 1~4 respectively may also be V, LG, R, W. Hope you took a pic of the sensor side or left some wire on the sensor-side connector, because the sensors are built by a subcontractor and the wires on the sensor side can be anything. Hope this helps.

Post by **dmiles140** » Sun Jun 06, 2021 4:53 pm

VStar650CL wrote: ↑
Sat Jun 05, 2021 8:20 pm
Here's the connections from the car side. You're looking at the back of the connector where the wires enter:

B53.png

There's some conflicting info about the wire colors, 1~4 respectively may also be V, LG, R, W. Hope you took a pic of the sensor side or left some wire on the sensor-side connector, because the sensors are built by a subcontractor and the wires on the sensor side can be anything. Hope this helps.

VSTAR

My colors were V, LG, R, and W. Everything is matching up correctly. I took it apart and even reconnected the original connector and I'm still getting the c1915 code along with c1138 and c1686. The only thing I can think of is when I took the sensor or the actuator. Do you know if the sensor have to line up a specific way?

Post by **VStar650CL** » Sun Jun 06, 2021 5:17 pm

Yes, it's a rotary potentiometer so it will certainly be sensitive to exact position.

Post by **dmiles140** » Sun Jun 06, 2021 5:59 pm

Can I get it recalibrated?

Post by **VStar650CL** » Sun Jun 06, 2021 6:20 pm

Not sure, and I can't get into ASIST on a Sunday to find out. I'm a Nissan guy and not Infiniti, maybe one of the M guys here can help you out. I'm wondering if you didn't damage the sensor, though. C1915 is still a flatline code, not misadjustment.

Post by **M37SJoe** » Sun Jun 06, 2021 6:23 pm

Sensor Test Procedure.

Post by **dmiles140** » Sun Jun 06, 2021 6:26 pm

I had an extra sensor from a M35 actuator and tried that and got the same code. I spent all day yesterday and today trying to figure out where I messed up and I'm clueless. Thanks for the help tho. Much appreciated.

Post by **VStar650CL** » Sun Jun 06, 2021 6:29 pm

It's only a pot, there's no smartwork in it to get hurt electrically. Try reversing the wire order, maybe you mirror imaged them.

Post by **M37SJoe** » Sun Jun 06, 2021 6:36 pm

There is an M35 / M45 Rear Steering Assembly on Ebay. The Sensor is the same. The Motor is the same. https://www.ebay.com/itm/03-07-Infiniti ... m2663d40cd

This part would give you a spare Motor and Sensor if you think your Sensor is suspect.

Post by **dmiles140** » Tue Jun 08, 2021 4:55 pm

M37SJoe wrote: ↑
Sun Jun 06, 2021 6:36 pm
There is an M35 / M45 Rear Steering Assembly on Ebay. The Sensor is the same. The Motor is the same. https://www.ebay.com/itm/03-07-Infiniti ... m2663d40cd

This part would give you a spare Motor and Sensor if you think your Sensor is suspect.

M37SJOE

Do you remember how you matched the trailer connector?

Post by **M37SJoe** » Tue Jun 08, 2021 6:48 pm

I found some notes but thought I had made a wiring diagram. On the Sensor Pin 1 is RR Angle Sensor Power Supply, Pin 2 is RR Angle Sensor Sub, Pin 3 is RR Angle Sensor Main, Pin 4 is RR Angle Sensor Ground. My hand written diagram shows Pin 1 Wire is Color is Violet, Pin 2 is Wire Color is Light Grey, Pin 3 Wire Color is Red, Pin 4 Wire Color is White. To test your Rear Angle Sensor when it is removed from the car: Apply +5 vdc to Pin 1. Apply Ground to Pin 4. Touch a Multimeter (DC) to Pin 2 and 4 and rotate the Sensor. You should see the voltage change from Min to Max. Repeat with the Multimeter (DC) on Pins 3 and 4 and you should get a similar measurement in voltage from Min to Max. It is probable that the Wire Colors are on the Wiring Harness side of the connector and not the Sensor side of the connector. I think the sensor wire colors can vary. The Signals on the original connector would not change.

Post by **M37SJoe** » Tue Jun 08, 2021 7:07 pm

This might help too...

VCC is Power.

Post by **dmiles140** » Tue Jun 08, 2021 7:48 pm

[/img]

dmiles140 wrote: ↑
Tue Jun 08, 2021 4:55 pm

M37SJoe wrote: ↑
Sun Jun 06, 2021 6:36 pm
There is an M35 / M45 Rear Steering Assembly on Ebay. The Sensor is the same. The Motor is the same. https://www.ebay.com/itm/03-07-Infiniti ... m2663d40cd

This part would give you a spare Motor and Sensor if you think your Sensor is suspect.
M37SJOE

Do you remember how you matched the trailer connector?

Here's a pic of my sensor connector and harness connector. So the harness side is pin 1-V, 2-LG, 3-R, and 4-W? Sensor side should be pin 1-Y, 2-R, 3-G and 4-Blk?

Post by **VStar650CL** » Tue Jun 08, 2021 8:25 pm

The colors on the car side don't match the ESM (figures!), but you should just be able to match color to color as they are in the mated connectors, black to white, red to light green, green to red, yellow to violet.

Post by **dmiles140** » Tue Jun 08, 2021 8:28 pm

That's what I did and I can't seem to get it to work.

Post by **VStar650CL** » Tue Jun 08, 2021 8:58 pm

dmiles140 wrote: ↑
Tue Jun 08, 2021 8:28 pm
That's what I did and I can't seem to get it to work.

Then if you're sure the splices are solid, the problem can't be wiring. Check the 5V power and ground and make sure it has both. Otherwise it has to be something mechanical that happened when you took the sensor loose, and if it isn't damage, it has to be the mounting angle. I know those things aren't supposed to be removed, they're part of the assembly and calibrated at the factory. For the same reason there's no calibration spec, they're not supposed to be serviceable. So if that's the problem, it may be a lost cause.

Post by **M37SJoe** » Wed Jun 09, 2021 4:07 am

Your wiring looks correct. Like VStar650CL suggested, check the +5vdc and Ground signals. If they are good, remove the Sensor and perform the Sensor test that I previously outlined. You need to verify the Sensor is good. Do you have a Multimeter and know how to use it? You can buy a basic el cheapo Multimeter for about $25.00. I use a Fluke Multimeter but it is much more expensive (~$300.00).

Post by **VStar650CL** » Wed Jun 09, 2021 4:22 am

M37SJoe wrote: ↑
Wed Jun 09, 2021 4:07 am
You can buy a basic el cheapo Multimeter for about $25.00. I use a Fluke Multimeter but it is much more expensive (~$300.00).

No need to google, either. Walmart sells perfectly good ones for $20~30.

Post by **dmiles140** » Sat Jun 12, 2021 11:11 pm

Thanks guys for the help. I finally got a chance to get back to working on the car. I ended up buying a used rack just because it was the last one and I figured 1k is alot less than 6k. I checked the 2 sensors I had, 1 from my car and 1 from the M35 rear actuator. They both measured off when I did the test.

The 1 from the M35 measured
Pin 1-4 0.93 (Good)
Pin 1-3 1.43 (Good)
Pin 1-2 0.49 (Bad)

I noticed that when I turned the spring on the inside of the sensor the value of 1-3 and 1-2 pins changes. The codes that I got that pertained to the rear angle sensor were C1915 and C1918.

So C1915 wasn't actually dead, it was an error with the main signal of the rear angle sensor and C1918 is the output of the main and sub are different.

Post by **dmiles140** » Sat Jun 12, 2021 11:28 pm

I decided to unscrew the rear angle sensor and hand turn the sensor while it was still attached to the actuator and check to see if the values changed. Sure enough, when I checked the multimeter, as I turned the sensor, pins 1-2 and 1-3 started changing. I kept turning until both values were within range and close to even as possible. Then, I started the car and noticed the 4was and traction light were off. I rescanned for codes after clearing them before I started the car and find nothing. All codes are clear and everything is working correctly now. The dealership could have easily troubleshooted this but instead recommended me spend 6k on a part that wasn't bad.

Post by **VStar650CL** » Sun Jun 13, 2021 5:33 am

dmiles140 wrote: ↑
Sat Jun 12, 2021 11:28 pm
The dealership could have easily troubleshooted this but instead recommended me spend 6k on a part that wasn't bad.

I figured it had to be mechanical if you had the wires right, but nice work with the ohmmeter to get it back in calibration!

Absolutely nobody wants to deal with 4WAS issues. From a tech's standpoint it's a sketchily-documented PITFA. It's sad but predictable that they'd want to throw new parts at it.

Post by **M37SJoe** » Sun Jun 13, 2021 6:15 am

Great job troubleshooting the problem! I am glad you finally figured out what was wrong. I am sorry you had to buy a used rear steering rack. I agree with the statements about the lack of documentation on the system. I think the Motor is a cheap Motor and should be better. I also question why there are two Signals from one Sensor and logic that compares the two signals that when it differs by 1 volt, creates a fault. Either two sensors or a single sensor with different fault logic would be better. The system is mechanically limited by how much steering angle can be applied anyway. Good work! If you need to replace mufflers contact me for what I did to put in a better system and save money.

Post by **VStar650CL** » Sun Jun 13, 2021 7:40 am

M37SJoe wrote: ↑
Sun Jun 13, 2021 6:15 am
Either two sensors or a single sensor with different fault logic would be better.

I can explain that part, it's a standard engineering failsafe. If you look in the ESM, you'll find the TPS and APP sensors use variations of the same thing. The TPS uses two pots with equal resistances but working in opposite directions, the APP uses two with slightly different resistances working in the same direction. In each case the pots double-check one another so the controller can tell if one is lying or dead, and because the percentage difference in slope is always the same regardless of supply voltage, it makes the sensors completely immune to variations in the power supply.

Post by **M37SJoe** » Sun Jun 13, 2021 11:03 am

VStar. You make a valid point. But enhanced failsafe engineering relies on diversity of sensors so they both don't exhibit the same FEMA. Having redundant different sensors would be better IMHO. But the main thing is that dmiles fixed it! and maybe we helped just a little...

Post by **VStar650CL** » Sun Jun 13, 2021 11:17 am

M37SJoe wrote: ↑
Sun Jun 13, 2021 11:03 am
VStar. You make a valid point. But enhanced failsafe engineering relies on diversity of sensors so they both don't exhibit the same FEMA. Having redundant different sensors would be better IMHO.

Yes and no. Separate sensors would require either tight external tolerances or sensor calibration, which could leave the controller in the same situation as the man with two watches, never knowing exactly what time it is. Having the two pots on the same shaft obviates that, but still provides protection against power vagaries. In an aircraft I'd probably advise doing both, but the 4WAS isn't an MCAS that's going to squash 300 people into mudpies by not being redundant.

M37SJoe wrote: ↑
Sun Jun 13, 2021 11:03 am
But the main thing is that dmiles fixed it! and maybe we helped just a little...

Amen, and thank you.

Post by **M37SJoe** » Sun Jun 13, 2021 11:22 am

VStar - We could debate this endlessly but it is beginning to sound like work! I do Safety PLC's for a living and am a Certified Functional Safety Engineer... whatever that means.

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