Cruise/ACC not working: two beeps, ACC OFF error

[MrFixit]

What the heck? Has anyone else had this issue? Does anyone know of a good resource that will show me where all the parts involved in the cruise control are? And any wiring diagrams for this?

There are several references to this condition in the manual:



I have also attached a few technical documents related to the ACC. I have some wiring diagrams too, but that level of detail is quite hard to follow. Replacing the ECU sounds like a drastic and wild guess to me that is unlikely to solve this...

 

[squishycans]

Right. I saw there are a lot of conditions for the ACC not working, including the "slope too steep". But the problem is it would always show the slope too steep, when I'm not on a slope or when I'm on level ground. That's not supposed to happen and something with the system is malfunctioning

I would love the wiring diagrams. I have an electrical engineering background and fix electronics for a living, so if it can help, I can probably figure out some stuff that will get me in the right direction to solving this.

 

[squishycans]

Hmm, I'm going to try Honda and see if they will help me. If not, I'm going to get rid of the car and go back to my beater for awhile.

 

[insightman]

Hmm, I'm going to try Honda and see if they will help me. If not, I'm going to get rid of the car and go back to my beater for awhile.

Do you plug in your Clarity PHEV so you can drive it on electrical power instead of gasoline? Do you not consider that an unrivaled benefit? Or is your beater an old Tesla with lifetime free charging? If you stick with your Clarity for a while, you'll probaby grow to like it very much.

 

[ClarityBill]

I would love the wiring diagrams.

There is a subscription website that is pretty good with electrical diagrams, and repair information for the Clarity (and most other cars).

alldatadiy.com

 

[squishycans]

Do you plug in your Clarity PHEV so you can drive it on electrical power instead of gasoline? Do you not consider that an unrivaled benefit? Or is your beater an old Tesla with lifetime free charging? If you stick with your Clarity for a while, you'll probaby grow to like it very much.

Honestly, I don't drive that much - ~4,000 miles a year roughly. My gas fuel costs with my 20 mpg car would be less than $1,000 a year (and $500 less car insurance). But I'm getting kind of sick of having a car. I'd rather drive something small and easy to maintain and fix, but everybody on the road around here drives these big cars and they all speed around like they are in a Nascar rally. I want to blame the New Yorkers for all coming here and overpopulating and making housing costs rocket up, but it's probably not just them. I might just get one of these https://powersports.honda.com/motorcycle/sport/cb300r (85.3 mpg to clarity's 110 MPGe, apples to oranges, but generally that's pretty close) and wear full motorcycle body armor.

 

[squishycans]

Well, if anyone is curious, MrFixit was super helpful and let me look at some schematics, which "seems" to narrow the problem down to the VSA or ECU.

So I bought the AP200 he suggested and just got it today and started looking over some things. The VSA has a sensor called "longitudinal accelerometer", which does indicate when the car is on an incline or decline and is supposed used to calculate pitch (I tried it with live data running and it does change depending on whether the car is angled up or down). However, it reads fine.

I also checked the ACC autocancel log and they all say 0, which indicates it's not autocanceling, just showing a cruise control preventing message you'd normally see on a steep incline.

And after opening a case with Honda, they just linked me to https://techinfo.honda.com/rjanisis/logon.aspx which is $25 day and probably won't help. So they only seem to care about taking my money. I guess that sounds about right actually.

At this point I suspect the ECU is malfunctioning, but I can't be certain and I refuse to spend money on parts in the hopes it fixes it, so I'm just going to get rid of it. Maybe this helps somebody else. :shrug:

 

[czbo]

I have a 2019 Clarity Plug-in Hybrid and getting the slope too steep error when attempting to engage ACC. The problem was intermittent, then other error messages showed up when starting the car: vehicle stability assist problem, brake system problem. Those error messages were intermittent also. The dealer replaced the VSA modulator and the slope too steep error is still there.

 

[MrFixit]

I have a 2019 Clarity Plug-in Hybrid and getting the slope too steep error when attempting to engage ACC

Sadly, the other person reporting this (@squishycams) gave up on the problem and seems to have gotten rid of the car and left the forum.

I assume you are no longer under warranty? This could get expensive as the dealer plays 'swaptronics' trying to solve it replacing things hoping to eventually stumble on the defective part.by

Did replacing the VSA get rid of all the other problems? Has your dealer weighed in on the next step they would take since their 'repair' did not fix the problem? Sometimes you can convince a dealer to not charge you for a repair that doesn't fix the problem (or, at least give you some credit toward the eventual repair that does fix it). Hopefully they have a pretty good idea of what to try next.

It always amazes me that with this level of electronics and internal diagnostic capability how often dealers end up guessing what the actual problem is and solving it by trial and error. Sometimes they don't know how to use the diagnostics effectively, or they are not trained to do so. In fairness, the Clarity is very unique and has a very low production volume so dealers will never be able to master it like they would with an Accord or Civic.

 

[czbo]

I have extended warranty so the cost should be covered. Dealer says the VSA modulator is a $2000+ component, yet a quick search online shows I can order one for about $750. The car is presently at the dealer and I am gussing they are trying to figure out the next steps. I asked them about possible wiring damage or water intrusion, and hand me the original VSA modulator, but visually all seems fine. The problem started 3 months after I moved from NY to OR. The car is now parked on an inclined driveway. The problems seem to occur more frequently when starting the car in the morning while sloped up. If I drive it to work and parked on flat ground for the day, I have not encountered the VSA problem or the brake system problem. The ACC would sometimes work for 5 to 10 minutes going home from work and then suddenly disengage saying slope is too steep while the car is in motion. Oregon winter is 90% rainy and high humidity with milder temperatures in the 40-50F. NY winter is freezing and low humidity. That's why I was thinking the intermittent issue is related to weather or environment or having the car parked on an incline.

 

[MrFixit]

hand me the original VSA modulator

Did he actually give you the original part? I thought they were required to give you the old parts (if you ask for them), only when you are paying for the repair. (ie: they do not have to give you old parts when it is a warranty repair)...

Hopefully they will figure this out for you. It is always more difficult to find something that is intermittent because often the problem doesn't present itself while the dealer has the vehicle. This is a very odd problem where it seems like your car is on a slope (when it isn't). Of course, it would not be unusual for a warning message like this to be totally misleading and may have nothing to do with apparent slope.

Please keep us posted... It is lucky you have the extended warranty. I never purchase extended warranties on things, BUT I did for this vehicle !!
Mine has been totally trouble free, but I was concerned about the novelty of this car, and the lack of any aftermarket parts.

 

[czbo]

I got the car back from the dealer yesterday (was with them for 1 week). It was fixed. I got the original VSA modulator they removed. After they replaced the VSA modulator, they test drove the car and still the cruise control gave the hill too steep error. It took them a few days to diagnose the problem and found error codes in the electric brake servo unit saying the upper and lower brake pressures were wrong. Pressure reading was high and far apart for the upper and lower pressure readings with brake pedal at rest. After they replaced the electric brake servo unit, the pressure readings were close to 0 with brake pedal at rest and the hill too steep error went away. The electric brake servo unit is covered under the Honda battery warranty.

 

[MrFixit]

I got the car back from the dealer yesterday (was with them for 1 week). It was fixed. I got the original VSA modulator they removed. After they replaced the VSA modulator, they test drove the car and still the cruise control gave the hill too steep error. It took them a few days to diagnose the problem and found error codes in the electric brake servo unit saying the upper and lower brake pressures were wrong. Pressure reading was high and far apart for the upper and lower pressure readings with brake pedal at rest. After they replaced the electric brake servo unit, the pressure readings were close to 0 with brake pedal at rest and the hill too steep error went away. The electric brake servo unit is covered under the Honda battery warranty.

Excellent...
After going through the aggravation, at least you have what is probably a perfectly good VSA modulator as a reward !
It looks like new ones sell for around $1500.

 

[czbo]

It was relatively painless. Good thing I purchased the extended warranty. The dealer gave me a loaner car to drive while the Clarity is with them. I had to pay for 1 hour of labor because the extended warranty did not cover all the labor involved with the VSA modulator.

 

[KKG]

This started 350 miles into a 500 mile road trip yesterday. 2018 Clarity PHEV, 1,950 miles. First time stretching its legs since I bought it a few weeks ago.

Cruise control will not engage in ACC or standard mode.

Main is on, dash displays ACC/LKAS. Trying to set ACC results in two short beeps and ACC OFF on the dash.

Switching from ACC to standard cruise by holding the distance button, standard cruise will not engage either.

Turning ACC off/on using the Main button or power cycling the whole car does not fix the issue. I turned the car off/on three times and it's still happening.

I gave the Honda badge sensor a wipe down, turned LKAS/collision mitigation off and back on, that stuff all seems to work fine.

Any ideas?

I am having the exact same problem on my 2018 Honda civic touring. I tried everything except going to the dealer yet. Problem is still not solved.