Hello all. LONG time lurker, VERY infrequent poster.

2007 HCH, 204k+ miles, only issue was an IMA battery replacement 2 years ago, so it's been a reliable car.

Over the past few months I have noticed some pulling to the left while driving (interstate, but not super fast due to lots of construction!). So I, of course, check the tires, brakes, etc. Nothing. I take it in for an alignment.

It takes them FOREVER to align the car because, when up on the rack with free wheel movement, they cannot center the steering wheel. It keeps turning left slowly until the end of travel. (They claimed it would do the same to the right, but were unable to get it to do it while I was watching.)

I did a lot of reading on our trusty interwebs and did the "reset torque sensor neutral" procedure a couple of times. Issue persists.

Since the car is off the ground and not moving when this happens, but the engine is running and EPS is active, I'm assuming that this is either a torque sensor issue or the EPS control unit issue? However, there is not, nor has there ever been an EPS warning light. No flash codes on EPS when jumpering the OBD-II either. Steering seems perfectly fine and responsive other than the consistent leftward tug.

Does it happen that there can be nothing wrong code/light wise, yet something IS wrong? Which is it more likely to be? The control unit or the torque sensor?

Thanks for any ideas!

Matthew

 

First, I'd pull the EPS fuse and re-check the alignment.

Also, drive w/o EPS fuse and see if it persists.

On the earlier Insights, there was a ground strap from the EPS unit to the chassis. This rarely went bad or cause problems, but perhaps it's an issue here.

Other than that, I got nothing.

 

Thanks S Keith!

Unfortunately there is no way to really pull the EPS fuse. It is a double fuse with one pole going to the battery then two poles fused to main power and EPS. Oddly, if you unscrew the EPS side and put a piece of paper or other insulator in there to keep it from making contact, it somehow kills the main fuse as well, so nothing will happen in the car.

Nevertheless, you CAN turn off the EPS in a roundabout way. If you go through the EPS reset procedure, but instead of turning the key off, start the engine, the EPS will fail and you get non-assisted driving. At which point the car drove perfectly fine and straight, just without any assist to the steering.

I examined what I can see of the EPS controller both under the dash as well as in the pictures in the service manual that I got a few years back when my dealer got new ones. There doesn't appear to be a ground strap anywhere, but there is a huge metal bracket that provides ground through three separate points. All bolts are tight, so one of those suckers is surely providing ground.

I reset the EPS again the correct way to turn it back on and all was back to power assist and pulling to the left. I even tried to trick it a bit by resetting the torque neutral about 5-10 degrees to the right instead of at the center. I didn't figure it would work given how the system functions, and it didn't.

Any other thoughts anyone? I'm wondering if I should just change the EPS control unit just to see if it works. It's only $60 on eBay and a couple of hours of frustration to get the old one out from behind the dash and the new one installed. :-/

Matthew

 

Sounds like you have a firm grasp on the situation. I'd say you confirmed it's the EPS system.

The ground strap (if it has one) is on the actual EPS drive unit.

Any luck with troubleshooting charts? IIRC, the manual has symptom based troubleshooting in addition to DTC.

 

Oh! I misunderstood that it's on the actual drive unit. I'll see what I can find.

I have not had the opportunity to go through the symptom list. I just noticed it was in the service manual last night and I want to set aside a chunk of time to go through it step by step. I'm glad you pointed it out.

Thanks for the help!

Matthew

 

Also a good time to ensure your main (-) cable and the two ground straps (engine to passenger side engine mount and transmission to driver's engine mount) are in good shape.

Not likely to be the source of the issue, but they corrode internally and can start causing problems across multiple systems.