speedometer problems

[KAIMIKAZEE]

just recently my speedo was spiking and then it stopped working...

my trip meter and mileage had also stopped working also....

what could be problem???

[bob h]

just recently my speedo was spiking and then it stopped working...

my trip meter and mileage had also stopped working also....

what could be problem???

vehicle speed sensor

[KAIMIKAZEE]

yes i was kind of leaning toward that....

i heard it was behind the tranny where the drive shaft connects..

but what does it look like????

[bob h]

yes i was kind of leaning toward that....

i heard it was behind the tranny where the drive shaft connects..

but what does it look like????

2 to 4 wires come from over top (or side) of transmission... it is either threaded in and locked with a jam nut, or bolted with a retainer. it is at the rear of the transmission at the output shaft

[Maniac]

It threads in AND has a locknut, and a plug with the wires, you can change it out in 15 minutes.

Just ask the parts guy how many turns to back it out after it bottoms out, I can't remember, BUT I think its one turn.

Last time I changed mine it was around $30.

[bob h]

quote="Maniac"]It threads in AND has a locknut,

it has a jam nut, as i stated above.

locknuts have distorted threads or nylon rings that stop a fastener from backing off completely after becoming loose

and a plug with the wires, you can change it out in 15 minutes.

Just ask the parts guy how many turns to back it out after it bottoms out, I can't remember, BUT I think its one turn.

Last time I changed mine it was around $30.[/quote]

bottom it out, then back off a 1/2 turn

[KAIMIKAZEE]

cool thanks guys, i just found where the sensor is...

will be digging it out tomorrow....

yeah peterbilt quoted me $43 for the sensor...

[possum squat]

are there usually 2 (or more) speed sensors?
is this speed sensor the same as the one used for other sub systems?

[bob h]

quote="possum squat"]are there usually 2 (or more) speed sensors?

no... ...depending

is this speed sensor the same as the one used for other sub systems?[/quote]

it's a magnetic pulse generator..., if that's what you mean.

abs sensors as well as some engine speed sensors are the same type of sensor

[KAIMIKAZEE]

well finally pulled it out...

the tip had some fresh oil on it...

i only drove it for like a half mile than i parked....

speedo works...

couldn't really go far because of the weather....

hope that oil on tip isn't an issue?????

[bob h]

well finally pulled it out...

the tip had some fresh oil on it...

i only drove it for like a half mile than i parked....

speedo works...

couldn't really go far because of the weather....

hope that oil on tip isn't an issue?????

is it possible to see the tip of the sensor after it is installed? i'm guessing NO. if this is correct than the sensor is threaded into the tailshaft housing and runs in an oil bath... normal.

if it leaks, you can thread it back out and install a new gasket

[KAIMIKAZEE]

yeah it would be possible if it weren't so cold to see the sensor tip again...

so it's normal to be soaked in oil...

what could've had caused that to fail?????

like you said, it's pretty much a maganet...nothing electrical...

[bob h]

quote="KAIMIKAZEE"]yeah it would be possible if it weren't so cold to see the sensor tip again...

so it's normal to be soaked in oil...

what could've had caused that to fail?????

like you said, it's pretty much a maganet...nothing electrical...[/quote]

some sensors are internal and some are external to the transmission... the sensors that are internal are threaded into the trans tailshaft housing and are exposed to the oil in the trans... it is normal for these to have oil on the tip

externally mounted sensors are mounted in about the same location but they thread into an ear or bracket and when you thread them in, you can watch the tip come in to contact with the tone ring (notched tooth wheel on trans output shaft), and these are not exposed to the trans fluid, and therefore it is not normal for them to be wet

the pulse generator is a magnet wrapped in a wound coil... yes, they're electric