1999 Chevy Blazer Lost drive, overdrive

RICHBARNES

MEMBER
1999 CHEVROLET BLAZER
6 CYL
4WD
AUTOMATIC
130,000 MILES

I recently lost the ability to shift into drive and overdrive. The transmission works fine from a stopped position, until it goes to shift into drive. It acts as though that gear doesn't exist. I had to drive it about 15 miles back home in 3rd, and upon returning home the fluid smelled very hot. Am I going to need a new transmission? Thank for the time. I have only put about 30k miles on this vehicle. The engine was replaced when I purchased it with a new crate motor. I have not changed the transmission filter since I have owned it. This problem also seemed to start at the same time as I had to replace the Throttle Position Sensor due to a engine code.

5 Replies

BMRFIXIT

MECHANIC
19,053 POSTS

You should be getting a check engine light on
and if so have to have it scanned for codes
let me know what you have for codes
also if to be using a scanner check for tranny codes
and OBDII codes will be ok too
let me know

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Monday, May 11th, 2009 AT 9:54 PM

RICHBARNES

MEMBER
3 POSTS

When I replace the throttle position sensor, the people at the autoparts store told me that the code had to reset itself. Is this correct? Or will I have new codes now?

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Tuesday, May 12th, 2009 AT 5:09 AM

BMRFIXIT

MECHANIC
19,053 POSTS

You should have a new codes know
plus you should've reset the codes after the repair was done
check for codes 1st let me know what you have

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Tuesday, May 12th, 2009 AT 5:25 AM

RICHBARNES

MEMBER
3 POSTS

The new code I received was P1870. It was in twice.

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Saturday, June 13th, 2009 AT 8:16 PM

BMRFIXIT

MECHANIC
19,053 POSTS

DTC P1870: TRANSMISSION COMPONENT SLIPPING

Circuit Description
PCM monitors difference between engine speed and transmission output speed. In D3 with TCC engaged, engine speed should closely match transmission output speed. In D4 with TCC engaged, TCC slip speed should be -20 to 50 RPM (all models except Corvette) or -20 to 40 RPM (Corvette). DTC P1870 is set if PCM detects excessive TCC slip when TCC should be engaged.

Action Taken By PCM
PCM performs the following if DTC is set:
Will illuminate MIL at second consecutive failure signal.
Inhibits TCC engagement.
Inhibits 4th gear if in hot mode.
Freezes shift adapts from being updated.
Commands maximum line pressure.
DTC P1870 will be stored in PCM history.