Speedometer is possessed.

[ravingmadman]

We'll be doing 60-70MPH, and the speedometer will regularly, randomly fall by ~20MPH and immediately go back to whatever speed we're doing. Like a nervous tick. I haven't looked into it, I don't even know if these things are electric or cable operated, but either way, it doesn't do it driving around town, or taking long trips at 35 on backroads. Only on the freeway. Anyone got any ideas?

[AtomicHoe094]

hmm, well it is electrical to answer one question.. maybe something that senses it in your tranns is out of wack..

[XLdenaliXL]

yea deff sounds like the speed sensor on the tranny

["350Vortec"]

Dad has this problem, We cleaned the speed sensor on the rear axle because it was corroded. Worked fine afterwards.

[ravingmadman]

I pulled all the fuses and replaced them, because i had a bunch of extras, and they're cheap, and then i pulled all the harnesses I could reach off, and cleaned them, and put them back on. Whatever I did fixed it. Thanks for the input!!!

[ravingmadman]

Forgive the thread necromancy; this has been an ongoing issue. This used to happen only when it was really cold, or when I took a really hard left turn (insert "you know you drive a tahoe when" joke here).

My Hoe is now undriveable, because the speedo is going all over the place, all the time. If I'm doing 60 up a slight hill on the interstate, and hit a bump, the speedo will dip to 20mph. The tranny then naturally heads for first gear to tackle the mountain it thinks I'm ascending. That's pretty crappy for my driveline. Since I have to immediately get off the gas to keep the engine from killing itself, I can't maintain freeway speeds. So, the Hoe's in the shop. I'll keep y'all posted on the diagnosis and the fix, since I'm not alone with this issue. FML
:drunk:

[rican4lfe]

when that happen in my 97 yukon I ended up changing the transmition speed sensor

[ravingmadman]

The shop just called and said they read the data stream while driving it, and it looks like the transmission speed sensor. Hmm. Is there an echo in here? (Thanks, Rican. :) )

[bowtiefreak]

I would have guessed it was a gremlin, sneaky little bastards. According to my son we have them in my house so beware.

[rican4lfe]

u welcome when that happend to me I went crazy...... but I went ahead an rebuild the transmission in the process.....

[ravingmadman]

Heh. Right. So on my way home, after paying the shop $230 to fix it, it still isn't fixed. I hate electrical problems. This is not going to be cheap. I did a super kick ass power slide getting onto the freeway though. :headbang: I caught a green light turning left onto the onramp- I started into the corner, the speedo died, my Bish shifted into first, the rear end broke loose, and I drifted around the corner. Fun, but I'd rather have some sort of control over it. FML

Maybe God is trying to tell me something, actually. The speedometer went out on my '06 GSXR600, too. Hm.....
:drunk:

[TheBeast99]

time to have that whole tranny and shit rebuilt and the rest of the electrical gone over?
i wish this anedote would help - i knew for a facr there was a problem with the onboard computer in my mom's old 1990 Buick Century when we were driving it to the mechanic for another problem (e-fan wasn't coming on) and while doing 50 the speedo just went to 0...
fortunately that car wasn't new enough for the speedo and tranny to be connected and shifting together n stuff, cuz we kept driving and it came back to normal a minute later :-P
but ya, just picture a 12-year old say that to their 'rents - "i think the computer's gone bonkers..."

[ravingmadman]

Ok. Another $375 at the shop. They traced the wires from the speed sensor up through the harnesses, load testing the wires at every junction. They found a harness that had burned out. They replaced it, and I appear to be back on the road. I'm doing a lot of driving this weekend through several mountain passes, so we'll see if it holds up.... I guess I still haven't put into this rig what I would be paying in interest and for full coverage insurance had I financed something...
:headbang: