I need some help

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09-15-2005, 12:56 AM

olli251

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Join Date: Sep 2005

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I need some help

hello, i have a 1997 blazer 4x4. The problem is that while crusing at low to moderate speed, the speedo drops to zero, the abs light comes on and the tranny locks into second gear. this is an interrmitant problem, and i have no clue whats causing this, i thought maybe a bad vss or exciter ring, if anyone else has had this problem it would be greatly appreciated for any advice. i have been told that my ignition switch could be bad? I thought that if that were the case, all my instrument panel would gor dead, but only the speedo goes dead.

thanks matt

09-16-2005, 07:25 PM

Joshua M. Smith

Join Date: Sep 2005

Posts: 7

Joshua M. Smith is an unknown quantity at this point

RE: I need some help

Hello,

Does your cruise control work?

Josh <><

09-18-2005, 01:15 PM

swartlkk

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Join Date: May 2005

Location: Waterloo, NY

Posts: 41,137

RE: I need some help

I'm thinking that the VSS is your problem. From AllDataDIY.com:

Quote:

The Vehicle Speed Sensor (VSS) is a pulse counter type input that informs the VCM how fast the vehicle is being driven. The VSS system uses an inductive sensor mounted in the tail housing of the transmission and a toothed reluctor wheel on the tail shaft. As the reluctor rotates, the teeth alternately interfere with the magnetic field of the sensor creating an induced voltage pulse.

The VSS produces an AC voltage signal that increases with the vehicle speed. The VCM processes this signal and sends it to the following components:

* The instrument panel
* The cruise control module

Advanced Autoparts shows 3 different VSS, one of them is for the 5spd. The other two (~$43 & ~$30) would need to be matched up with your current sensor to ensure compatibility.

These newer electronically controlled transmissions are very sensitive when it comes to readings from sensors. It is quite possible that your sensor has gotten dirty and just needs to be cleaned. I would try this first before dropping $$$ into buying a new sensor.

For reference, the sensors are:
GP Sorensen 7799517 - Speed Sensor - $42.96
GP Sorensen 7799588 - Speed Sensor - $29.88

I'm sure that one is for the 4wd and the other for the 2wd, but Advanced Auto's website does not differentiate between the two. I'm sure your local store can help you out with that determination.