Weird Throttle Response when w/ turn signal on.
Thread Starter
Junior Member
Joined: Oct 2016
Posts: 59
Likes: 5
From: Central PA
1986 Porsche 911 Coupe, a 2002 CLK320 & 2013 C300
Weird Throttle Response when w/ turn signal on.
Okay guys, need a little bit of help. I'm pretty handy with my diagnosing but over the last couple of weeks I've got something that simply does not make sense to me. I noticed it first when cruising on the highway and I had the cruise control on. I'd go to switch lanes and I'd notice the cruise control would turn off as if I'd disabled it. It did this a few times until I realized what was happening. Basically the issue that randomly when I turn on the LEFT turn signal and my foot is on throttle the turn signal seems to interfere with the throttle, basically going off throttle when it blinks (it does it in synchronized fashion, really weird but that's why it's very noticeable) never does it when I turn on the RIGHT turn signal.
It's very repeatable when it does it, and then it goes away on it's own. Might come an go within a 20 minute drive on its own, where it does it and then it goes away. It's mostly noticeable at hwy speed since I'm on throttle but it will do it as well when I am stopped at a red light and have my left turn signal on and then give it throttle, it will hesitate in time with the turn signal. If I manually take the turn signal off the throttle response ALWAYS goes back to normal.
Again, weird stuff by I'm at a loss to even figure out where to begin to look. It does seem like an electrical issue where perhaps the two points get grounded somewhere and the act of putting on the turn signal searches for ground through the throttle by wire system.
Other than that, I've got no guess... Help.
It's very repeatable when it does it, and then it goes away on it's own. Might come an go within a 20 minute drive on its own, where it does it and then it goes away. It's mostly noticeable at hwy speed since I'm on throttle but it will do it as well when I am stopped at a red light and have my left turn signal on and then give it throttle, it will hesitate in time with the turn signal. If I manually take the turn signal off the throttle response ALWAYS goes back to normal.
Again, weird stuff by I'm at a loss to even figure out where to begin to look. It does seem like an electrical issue where perhaps the two points get grounded somewhere and the act of putting on the turn signal searches for ground through the throttle by wire system.
Other than that, I've got no guess... Help.
Thread Starter
Junior Member
Joined: Oct 2016
Posts: 59
Likes: 5
From: Central PA
1986 Porsche 911 Coupe, a 2002 CLK320 & 2013 C300
Today I cleaned the connection to the TPS and the did a TPS reset, with the procedure described online. I took a look at the visible grounds I could look at and made sure there were no blown fuses. One item of note there is no cruise control fuse in the front. Tomorrow I'll look at the back of the car.
Thread Starter
Junior Member
Joined: Oct 2016
Posts: 59
Likes: 5
From: Central PA
1986 Porsche 911 Coupe, a 2002 CLK320 & 2013 C300
It's the weekend and I have some time. Got sidetracked this week, but I'll dive in again. Given the number of views on the thread and the lack of response, I'm all the way out here in left field by myself. Was hoping someone would swoop in and say yeah, that same thing happened to me, it was really weird, here's the simple fix to is.
LOL not the case.
LOL not the case.
Thread Starter
Junior Member
Joined: Oct 2016
Posts: 59
Likes: 5
From: Central PA
1986 Porsche 911 Coupe, a 2002 CLK320 & 2013 C300
Follow up on this for the sake of the forum. After a lot of looking for a culprit and going nowhere, I started seeing bulb out messages with of course no bulbs being out. Yeah, I know about it always being the license plate bulbs, but there were no bulbs out. I also noticed that while I put my foot on the brake, the turn signal would "speed up" as if there was an LED bulb in use, but no LED bulbs. So I figured that since I'm getting a message for a bulb out, and now I have another thing pointing to the turn signal on I focused on those bulbs.
Turns out that the rear turn signal bulbs were in, were tight and would light but they were the wrong bulbs. The little "pips" that secure the bulb to the socket had been ripped off. The bulbs in there had the little tabs offset. The bulb was arching into the socket and creating a burn mark and I guess creating havoc with the CAN bus signal.
I've replaced the bulbs with the correct ones, after cleaning the socket and using dielectric grease on the contacts and the problem has gone away. It's been only a few days so far but I'm staying cautiously optimistic for now. No symptoms at all.
Turns out that the rear turn signal bulbs were in, were tight and would light but they were the wrong bulbs. The little "pips" that secure the bulb to the socket had been ripped off. The bulbs in there had the little tabs offset. The bulb was arching into the socket and creating a burn mark and I guess creating havoc with the CAN bus signal.
I've replaced the bulbs with the correct ones, after cleaning the socket and using dielectric grease on the contacts and the problem has gone away. It's been only a few days so far but I'm staying cautiously optimistic for now. No symptoms at all.
