Steering Assist Fault - Service Now. Seeking help from a tech/ideas on causes

[Austinj427]

Yeah I asked because I remember you were going to run the antigravity. For now I would try putting the stock battery back in just to remove that as a variable. I know the ATX12-24 has run fine on our cars, but when I tested one of the non-compatible batteries it gave a hill assist error, so I'd say it doesn't hurt to put the stock battery in just as a simple way to know you aren't chasing your tail.

This is a good idea.

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[JAJ]

Doesn't look like I have the ability to use ForScan to run the diagnostic tests, but I did throw a volt meter on the connectors. The 2-wire connector shows 13.6v on the red wire. The 3 pin connector shows no power across any of the 3 wires.

Well, even that's important. There are only six wires on the OBD connector: power, ground, the HS1 pair and the HS2 pair. The only way that Forscan (or IDS for that matter) can talk to anything is over those two CAN pairs. If there's a short or an open on HS1 or HS2 wire pairs (ie- mechanical damage to the wiring somewhere) then Forscan is unable to communicate, which is what you're seeing.

At this point, I'd turn everything off, and check with an ohm-meter between pins 2 and 3 on C1463A. Zero ohms means there's a short. Open circuit doesn't mean anything in particular, though.

That HS2 pair also passes through connector C1046, which is a 34-pin connector that's part of the engine wiring harness. I can't tell from the diagram whether it's on top of the engine or underneath, but have a look at it as well. The manual describes it as "Inline" which I think means it's a connector that joins one part of the wiring harness to another. It's on the passenger's side of the engine bay and it looks like it's part of the wiring harness that connects the Battery Junction Box (fuse box) to the engine.

 

[honeybadger]

Yeah I asked because I remember you were going to run the antigravity. For now I would try putting the stock battery back in just to remove that as a variable. I know the ATX12-24 has run fine on our cars, but when I tested one of the non-compatible batteries it gave a hill assist error, so I'd say it doesn't hurt to put the stock battery in just as a simple way to know you aren't chasing your tail.

No go. Original battery didn't change anything. I also physically checked every fuse in both boxes. No blown fuses.

Well, even that's important. There are only six wires on the OBD connector: power, ground, the HS1 pair and the HS2 pair. The only way that Forscan (or IDS for that matter) can talk to anything is over those two CAN pairs. If there's a short or an open on HS1 or HS2 wire pairs (ie- mechanical damage to the wiring somewhere) then Forscan is unable to communicate, which is what you're seeing.

At this point, I'd turn everything off, and check with an ohm-meter between pins 2 and 3 on C1463A. Zero ohms means there's a short. Open circuit doesn't mean anything in particular, though.

That HS2 pair also passes through connector C1046, which is a 34-pin connector that's part of the engine wiring harness. I can't tell from the diagram whether it's on top of the engine or underneath, but have a look at it as well. The manual describes it as "Inline" which I think means it's a connector that joins one part of the wiring harness to another. It's on the passenger's side of the engine bay and it looks like it's part of the wiring harness that connects the Battery Junction Box (fuse box) to the engine.

Will try to this tonight. I think Forscan is freaking out because of the custom AED tune and it is unable to identify the PCM.

 

[JAJ]

...Will try to this tonight. I think Forscan is freaking out because of the custom AED tune and it is unable to identify the PCM.

Possible but not likely. If that's the case, and you installed the AED tune from your X4, then you can return to stock and see if that fixes the problem.

You can tell that I'm looking at this as a module communication problem, not a module failure. There's no reason a module would fail when the car was apart, but with all the removal and installation work, it's possible that the wiring might be injured somewhere - pinched or cut.

Actually, now that I think about it, didn't you have a wiring harness problem a while ago? Am I remembering correctly? If you did, did you ever get it fixed?

 

[fmc_smt]

No go. Original battery didn't change anything. I also physically checked every fuse in both boxes. No blown fuses.



Will try to this tonight. I think Forscan is freaking out because of the custom AED tune and it is unable to identify the PCM.

I know ids will do this with my lund tune . If you don't have switched power at the pscm that would be why you have communication codes to the pscm in the bcm

 

[honeybadger]

Possible but not likely. If that's the case, and you installed the AED tune from your X4, then you can return to stock and see if that fixes the problem.

You can tell that I'm looking at this as a module communication problem, not a module failure. There's no reason a module would fail when the car was apart, but with all the removal and installation work, it's possible that the wiring might be injured somewhere - pinched or cut.

Actually, now that I think about it, didn't you have a wiring harness problem a while ago? Am I remembering correctly? If you did, did you ever get it fixed?

Yep. Replaced both harnesses entirely (engine cradle harness and engine harness).

Regarding Forscan, it's telling me that's the problem specifically. Don't want to mess with the tunes until after Dyno day. Will check the harness for continuity tonight, tho.

 

[honeybadger]

I know ids will do this with my lund tune . If you don't have switched power at the pscm that would be why you have communication codes to the pscm in the bcm

How do you get around it? Forscan asks for the PCM part # but won't accept any of the variations I put into it.

 

[fmc_smt]

With ids I have to reflash back to oem calibration .

 

[ZX3ST]

I also physically checked every fuse in both boxes. No blown fuses.

I don't mean to be dense, but do you mean you pulled them from the fusebox and looked? I've had several open fuses over the years that appeared fine via physical inspection. I use my meter and tag the tops of the fuses on both sides while they're still in the car - looking for voltage on both sides.

Just a thought. Knock out the stupid stuff first. Nothing's worse than chasing your tail for days when the answer could possibly be that simple.

 

[honeybadger]

I don't mean to be dense, but do you mean you pulled them from the fusebox and looked? I've had several open fuses over the years that appeared fine via physical inspection. I use my meter and tag the tops of the fuses on both sides while they're still in the car - looking for voltage on both sides.

Just a thought. Knock out the stupid stuff first. Nothing's worse than chasing your tail for days when the answer could possibly be that simple.

No worries at all. and yep. Pulled everyone and physically tested it with my tester.

Driving me nuts

 

[honeybadger]

Welp, I figured it out. Turns out the harness I got from Whitebearlake to replace my OEM one was a different part number. I bought JR3Z-14300-N, but needed FR3Z-14300-T. Turns out this one is on backorder with no visibility on delivery date. Whitebearlake was kind enough to issue a return label and will refund me the part even though it was installed. Awesome!

In the meantime, I've reinstalled the original harness and all appears to be good. No more power steering error and the computer seems happy enough. One less thing to worry about!

 

[JAJ]

Congratulations! Having the steering working will make it a lot easier to get to the dyno on Monday.

 

[TDC]

Congrats. Any chance of converting the incorrect harness to the correct one by switching pins?

 

[honeybadger]

Congratulations! Having the steering working will make it a lot easier to get to the dyno on Monday.

For sure. Thanks for your help along the way (and everyone else!). Always nice to get help from those that understand the deeper layers of the cars better

Congrats. Any chance of converting the incorrect harness to the correct one by switching pins?

I don't think so. There are quite a few differences.

New plug

Old plug

 

[JAJ]

For sure. Thanks for your help along the way (and everyone else!). Always nice to get help from those that understand the deeper layers of the cars better

There are quite a few differences....

Hey! I was happy to help! I'm glad you got it going! For a decade, decades ago, I designed and built very complex electronic control systems. Masses of wires and connectors. This stuff is easy for me to analyze, but I can only do so much by remote control

One thing to tuck away in your memory banks if you run into a problem like this again: If a complex system has worked correctly for long enough that you have confidence that it works, and then it stops working, it's extremely rare for there to be more than one thing that's actually wrong. Step back and ask yourself the question "what single thing could cause all these symptoms?". In this case, there were loads of diverse symptoms, but there was only one actual problem that caused them all - the wiring harness had the wrong part number.

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