Cruise Control just stopped working

[tturkstra]

Yesterday my cruise control wouldn't activate. I tried it about 10 minutes later and it started working. When it activated, I thought I heard a relay click under the dash - is that normal?

Today it's not working again. LED comes on on the column switch, but the set button doesn't activate it or make the green light come on on the dash. Any easy things to check before I dig out my service manual and try to start checking things? Search on prime didn't yield anything I could find. Note: 5-speed transmission.

 

[Miner]

Possible the brake / clutch pedal plastic button breaking up and starting to fall apart.

 

[Old Guy]

I agree with @Miner. The clutch and brake pedal switches are the first place I would check (everything else gets harder and more expensive). The clutch pedal has two switches. The infamous Switch B which is the upper switch which controls the starter interlock and the lower switch A which is the cruise control interlock. The pedal mechanism for switch A works in reverse to the upper switch. When the clutch pedal is released (up) the stopper on the pedal holds switch A closed so if the stopper falls out (or the switch goes out of adjustment) the switch goes open and the cruise control will fail to engage. The brake pedal switch operates the same way as the lower clutch switch. When the pedal is up it holds the contacts for the cruise switch closed so if the stopper falls out the contacts will stay open and the cruise will not set. The brake pedal switch has two sets of complimentary contacts. The other set is normally open and controls the brake lights which will stay on if the stopper falls out so that should be fairly obvious (leads to a dead battery fairly quickly).

Fortunately, the lower clutch switch and brake switch are 'easier' to get at to check and replace the stopper if required. The bad news is that if the stopper did fall out, you should probably plan for replacement of all three stoppers which includes the miserable upper clutch switch stopper! Right now no cruise control is a minor inconvenience. If the upper clutch switch stopper falls out the car will be in a no-start condition which may leave you stranded at the wrong time.

Do you have an aftermarket steering wheel? If so, and the clutch and brake switches are OK then I would be looking for problems with the set switch connection. At that point you should get a hold of the service manual and go through the control input tests for the cruise control because things are getting more complicated.

I am not sure about the click that you refer to. There is no external relay in the cruise control circuit that would make a click. It is possible that the cruise control unit has an internal relay which is used to control the electric clutch in the cruise control actuator. If that is the case and that relay is operating that could be a sign that the control electronics are working and the problem is with the actuator. That is a 'bigger' problem, so rule out the clutch and brake switches which are probably the more common problem.

 

[tturkstra]

Thanks for those excellent thoughts - I was hoping to get off easy. Unfortunately, all 3 spacers look fine. (They were already changed to the plastic type, I think the receipt said 2016.) Found these later:
http://www.nsxprime.com/forum/showthread.php/124118-The-1-55-Repair
http://www.nsxprime.com/forum/showthread.php/170645-Cruise-control-not-engaging

It no longer "click"s when I press the set button anymore - it only seemed to do that the one time it worked. I don't have an aftermarket wheel, but a previous owner did swap the airbag for a JDM one with a Honda logo so I'll have a look at the set/cancel buttons and maybe the clockspring, after I have finish perusing the cruise control section of my service manual. Looking at it, all the wires go back to the ECM, with no relays under the dash so I don't know what I heard.

 

[Miner]

The switch is pretty straightforward as I remember. A simple meter checking continuity at the connector under the dash; 3-wires. Hopefully something simple.

 

[tturkstra]

Follow-up. Went through the service manual, which has you check fuses & then each switch input at the ECU. Smart! Oddly, the set/resume switches both failed testing at the ECU (could also be clock spring or intervening wire), but the brake switch did too, which seemed odd since the brake lights work perfectly. I was about to pull the set/resume switch & replace it but my wife wanted to go for a drive this afternoon. Cruise control is now working again. Hmmm. I guess I'll be back to this thread if it stops working again.

 

[Old Guy]

Follow-up. Went through the service manual, which has you check fuses & then each switch input at the ECU. Smart! Oddly, the set/resume switches both failed testing at the ECU (could also be clock spring or intervening wire), but the brake switch did too, which seemed odd since the brake lights work perfectly. I was about to pull the set/resume switch & replace it but my wife wanted to go for a drive this afternoon. Cruise control is now working again. Hmmm. I guess I'll be back to this thread if it stops working again.

The brake light switch has two separate sets of contacts, one for the brake light circuit and one for the cruise control so its possible for the cruise control portion of the switch to fail without affecting the brake light portion. However, when the actuator button falls out, that causes problems in both circuits.

You likely have an intermittent connection someplace that you disturbed during testing which caused things to resume working. At least you got to go for a drive. This happened last Monday after everything had dried up and I was just about ready to get the NSX out of storage. Looks like NSX season got bumped by a couple of weeks.

 

[ShawnOT]

Besides the parts diagram, does anyone have some images or set of instructions for locating and replacing the 3 stoppers? My cruise isn't working and based on what I'm reading here and because I found the broken remains of one of the old plastic stoppers (had no clue what it was at the time), I suspect I need to replace at least one, so why not try to do all three.

Thanks

 

[tturkstra]

I just replaced the lower clutch stopper on the floor, 39 in that diagram, 46905-SK7-000, now in a lovely shade of Navy blue.
Have a look at the two threads referenced in post 4 for some good pics.
TT

 

[Old Guy]

If you search on Prime, you can find links for .pdf versions of both the 1991 service manual and a mostly complete version covering 1997 - 2005. In the electrical - brake lights section of the service manual on page 23-205 you will find a diagram which shows the switch / button locations for both the clutch and brake switches. I think there are also diagrams In the brake and clutch sections of the service manual covering the respective pedals.

If you remove the lower cover in the footwell on the driver side and then remove the driver side knee bolster
Dashboard Lower Pad removal (nsxprime.com)
you should have a good view of the switches and the buttons. The service manual provides no advice on how to replace the buttons - that is up to you. The only thing I recommend is stock up on some Robaxacet and try to persuade somebody under 20 to do it for you. You can search Prime for suggestions on how to do the upper clutch button (the worst one) if that is the one that failed.

 

[ShawnOT]

Thank you [MENTION=26435]Old Guy[/MENTION] and [MENTION=37580]tturkstra[/MENTION]

 

[ShawnOT]

I'm happy to report back that I got some of the new stoppers and it solved the cruise control issue. It required some body contortion that I wont be capable of in about 10 years, but not too bad considering I was expecting something way more complicated and/or costly. As expected, the lower stopper on the clutch pedal was completely missing. I could see the upper one way up in there and it looked old and yellowed, so one of these days when my back is in tip top shape I'll go after that one. Thanks again for the info on the PDF repair manuals, seeing the diagram of the pedals was really helpful.

 

[Miner]

Good job! The clutch, upper stopper is the hardest one to replace, and when it goes bad, starting the car will become a problem.
There are a couple suggestions on different threads about how to replace it.

 

[The King]

The brake light switch has two separate sets of contacts, one for the brake light circuit and one for the cruise control so its possible for the cruise control portion of the switch to fail without affecting the brake light portion. However, when the actuator button falls out, that causes problems in both circuits.

You likely have an intermittent connection someplace that you disturbed during testing which caused things to resume working. At least you got to go for a drive. This happened last Monday after everything had dried up and I was just about ready to get the NSX out of storage. Looks like NSX season got bumped by a couple of weeks. View attachment 169407

.

I feel your pain Old Guy! We haven't had any snow accumulation since early April, but it hasn't warmed up and never stops raining. Plus the roads look like a war zone, and the potholes could swallow up small cars. The NSX will remain in hibernation till who knows when:frown:.

 

[Old Guy]

.

I feel your pain Old Guy! We haven't had any snow accumulation since early April, but it hasn't warmed up and never stops raining. Plus the roads look like a war zone, and the potholes could swallow up small cars. The NSX will remain in hibernation till who knows when:frown:.

It had mostly dried up by the first week in April and temperatures were reaching into the 10 C range when a Colorado low blew in and dumped a pile of snow and overnight temperatures dropped down to -20C. Temperatures recovered a bit; but, not enough for melting and then there were two more repeat visits from our Colorado buddy over the next couple of weeks. In Regina we dodged most of the snow accumulation; but, south of us there were people in rural areas without power for 3 days because of power line structure failures because of ice accumulation. The TransCanada between Sask and Man was closed for at least two days.

About the middle of last week the weather gods cranked up the thermostat and combined with clear skies just about all of the snow has disappeared and the lane leading up to my garage has mostly dried up. The roads are never really good around here; but, on the up side because it was pretty much continuously cold during the winter there was pretty much no thaw - freeze which causes a lot of the pot hole failures - definitely glass half full on that one! Tentative plan is to go fetch the NSX from storage tomorrow :smile: .