Cruise control ?'s

Mypetropig

Original poster
Member
Dec 29, 2011
226
Never really paid any attention to this til now. My wife has been telling me that the cruise control doesn't seem to work until the engine is almost or at operating temp. Is this nornal or could there be an under lying cause. I recently replaced the cam position sensor if it matters.
 

Mooseman

Moderator
Dec 4, 2011
25,580
Ottawa, ON
Hook up a code reader and check for any pending codes. I had a P1345 that when pending, would disable the cruise. There are other codes that will do the same. Depending on any codes, you may need a CASE relearn with that new cam sensor.
 

Wooluf1952

Member
Nov 20, 2011
2,663
Milwaukee, Wisconsin
IIRC, you only need a CASE relearn if you change the crank angle sensor, not the cam sensor.
 

Mypetropig

Original poster
Member
Dec 29, 2011
226
I now realize that engine temp doesnt matter but speed does. I removed my brakes and checked my caliper guide pins and removed some glazing on the front disc's. It was shortly after burnishing them in that I realized my brake lights are acting funny and possibly keeping the cruise from working. Sometimes they will work fine and others they will flicker and not work properly. I am going to try the brake light switch, but was wondering where the brake light relay was located. Is it in the BCM under the back seat? The pic on rockauto is showing it to be like a little board.
 

MAY03LT

Member
Nov 18, 2011
3,422
Delmarva
Mypetropig said:
I am going to try the brake light switch, but was wondering where the brake light relay was located. Is it in the BCM under the back seat?

All we have is the switch, which, when switched, puts power from the ST/LP fuse 12 up front to VEH CHMSL fuse 16 and VEH STOP fuse 34 in the rear, which go to the brake lights.

Looks like that relay thing is use to turn on the light in the dash.
 

Mypetropig

Original poster
Member
Dec 29, 2011
226
MAY03LT said:
All we have is the switch, which, when switched, puts power from the ST/LP fuse 12 up front to VEH CHMSL fuse 16 and VEH STOP fuse 34 in the rear, which go to the brake lights.

Looks like that relay thing is use to turn on the light in the dash.

Thanks for the info, perhaps I will investigate a bit now that I know the order of things. The switch is only 13 bucks at the local auto parts store so I will pick one up just in case. As for the so called relay I was expecting an ice cube relay or something of the like. Good to know all we have is the switch, it makes things easier.
 

MAY03LT

Member
Nov 18, 2011
3,422
Delmarva
Mypetropig said:
perhaps I will investigate a bit now...

377dc3b7.jpg


Did you say investigate? Investigating is cool. You can see in this diagram that after fuse 34, the B+ signal not only goes to the L an R brake bulbs but also branches off and is an input to the pcm.
 

Mypetropig

Original poster
Member
Dec 29, 2011
226
That is cool. I have always been pretty good with mechanical stuff but for some reason struggle a bit with schematics. I eventually get it but not without frustration. The written description of the flow really makes it click in my head. I guess persistence on my part will be the key to reading them with ease at some point. Thanks again for the info, this really helps.:hail:
 

Mypetropig

Original poster
Member
Dec 29, 2011
226
I checked power to and through fuse #12 its good, power to and through fuse #16 its good, power to and through fuse #34 and its good. This voltage is present and I still have intermittent brake lights. When they fail to illuminate I see the CHMSL flicker. I would think the switch is good if I am getting power to fuses 16 and 34. Could it be the old neon CHMSL causing this?
 

MAY03LT

Member
Nov 18, 2011
3,422
Delmarva
Mypetropig said:
I checked power to and through fuse #12 its good, power to and through fuse #16 its good, power to and through fuse #34 and its good. This voltage is present and I still have intermittent brake lights. When they fail to illuminate I see the CHMSL flicker. I would think the switch is good if I am getting power to fuses 16 and 34. Could it be the old neon CHMSL causing this?

Think about it like this....voltage only goes through 16 and 34 when the switch is closed (pedal pushed). Once the pedal is released, the circuit is open again. The process repeats every time the pedal is pushed. So, with a crapping out switch, you could push/hold the pedal one time and have proper voltage through those fuses, the next push/hold you might not have anything. Or, because it's intermittent, it might be 50 pushes later. When the CHMSL flickers and you have no l/r bulbs, I'd want to see what the voltage is at pin A of the switch. I suspect that it wouldn't be 12v.

If you do go that route, it is 1000x easier to get that reading at the white wire at the flasher. The flasher is mounted to the plastic shield under the drivers side of the dash. If you look at the switch in the diagram, you'll see that after pin A, the circuit branches to the flasher as well as the rear fuse block.
 

Mypetropig

Original poster
Member
Dec 29, 2011
226
Since I already had the switch I decided to install it despite the fact that fuse 16 and 34 had power when the pedal was pressed :confused:. They are working now and I will find out tomorrow if the cruise will work consistently as well. I will post results later.
 

Mypetropig

Original poster
Member
Dec 29, 2011
226
MAY03LT said:
Think about it like this....voltage only goes through 16 and 34 when the switch is closed (pedal pushed). Once the pedal is released, the circuit is open again. The process repeats every time the pedal is pushed. So, with a crapping out switch, you could push/hold the pedal one time and have proper voltage through those fuses, the next push/hold you might not have anything. Or, because it's intermittent, it might be 50 pushes later. When the CHMSL flickers and you have no l/r bulbs, I'd want to see what the voltage is at pin A of the switch. I suspect that it wouldn't be 12v.

If you do go that route, it is 1000x easier to get that reading at the white wire at the flasher. The flasher is mounted to the plastic shield under the drivers side of the dash. If you look at the switch in the diagram, you'll see that after pin A, the circuit branches to the flasher as well as the rear fuse block.

I came inside several times to double check the schematic to see if I was missing anything (out of printer ink). I had my son press and hold the pedal for me while I checked voltage at 16 and 34. As I said, I had voltage on both of those fuses but no lights. I didnt even think to check voltage on pin A when they screwed up. I must say that you have been a huge help with this and I greatly appreciate it.
 

MAY03LT

Member
Nov 18, 2011
3,422
Delmarva
Mypetropig said:
Since I already had the switch I decided to install it despite the fact that fuse 16 and 34 had power when the pedal was pressed :confused:. They are working now and I will find out tomorrow if the cruise will work consistently as well. I will post results later.

What kind of tester did you use? DMM or test light?

Mypetropig said:
I came inside several times to double check the schematic to see if I was missing anything (out of printer ink). I had my son press and hold the pedal for me while I checked voltage at 16 and 34. As I said, I had voltage on both of those fuses but no lights. I didnt even think to check voltage on pin A when they screwed up. I must say that you have been a huge help with this and I greatly appreciate it.

Ah, I missed the part where the test was done with the pedal pushed while the lights weren't working.:redface:

Knowing that, "A" should have been the same as 16/34 and wouldn't have been tested next.

And no problem! Hopefully this was the fix. Outside of the brake switch circuits and several DTC's, cruise diagnosis involves a high end scan tool that can read cruise data. That's like anti-DIY lol.
 

Mypetropig

Original poster
Member
Dec 29, 2011
226
I used a DMM. I like them better because they show exactly how much power is present whereas I think test lights just show power, no matter how little. If this doesn't fix cruise also then it will just have to be inconsistent for a while because I don't have the funds to have it hooked up to a Tech II right now.
 

Mypetropig

Original poster
Member
Dec 29, 2011
226
My wife drove it around alot today and so far so good. :wootwoot:
 

Mypetropig

Original poster
Member
Dec 29, 2011
226
Its been almost a week and all is well :thumbsup:. Mark this thread solved.
 

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