many tranny codes bad gas milage

[wolvie]

2002 Trailblazer 4.2 have many tranny codes. Someone said check fuse 47 and did. 8.0 volts and fuse.
Gas milage about 6mpg.

 

[Sparky]

What codes? Need more info.

 

[wolvie]

PO740, PO753, PO758, PO785 PO1860 and then PD and same codes.

 

[Mooseman]

Transmission with multiple codes
Another Transmission with Multiple codes
More Multiple Codes

 

[wolvie]

Thanks for the good info. I will be checking wires and solenoids. Plan on dropping pan and new filter and fluids. I have 2 donor trailblazers and will use solenoids if possible.

 

[Kelly@PCMofNC]

Good luck. Does it shift okay or is bad gas mileage the only symptom you've noticed besides the codes?

 

[gmcman]

Does it start up in 1st or 2nd gear? You can place selector in 2nd from a stop and see if it drives away the same.

 

[wolvie]

Starts in 2nd gear and shifts to 4th it seems.
Did find a fuel leak above the fuel tank. Will pull tank and see whats up.
Fuel filter really bad and rusty.

 

[gmcman]

If your fuel filter is old, that could be the cause of poor fuel economy...along with having 2 gears.

Make a note of the lines to the filter, both will fit either side, filter has an IN and OUT port.

 

[wolvie]

Changed fuel filter now another leak coming near fuel pump. lots of rusty lines.
I will have it checked and drop tank.
Still many codes for tranny. Feel like maybe a mouse chewed on electric harness.
Found a big mouse nest and removed seats and carpet. Smelled bad. Slowly getting done.

 

[wolvie]

Is there a possible relay that is bad? Found some bad relays for lights and the starter relay was thrown in the glove box.

 

[Mooseman]

You would have to check the schematics to see how power to the tranny is controlled. You should check if power and ground are getting to the tranny.

 

[limequat]

Is there a possible relay that is bad? Found some bad relays for lights and the starter relay was thrown in the glove box.

No relays. The solenoids and TCC clutch are driven off a single power wire from ignition. Post ur MY and I'll tell you the fuse #. Also, what do you mean about 8.0V in the OP?

 

[wolvie]

No relays. The solenoids and TCC clutch are driven off a single power wire from ignition. Post ur MY and I'll tell you the fuse #. Also, what do you mean about 8.0V in the OP?

mwolvie@gmail.com rear fuse box (back seat} fuse 47 has power but only 8 volts not 12 volts.

 

[wolvie]

How do you remove wire harness to transmission to check for shorts. very little space.
I have a donor 2005 trailblazer I want to remove wire harness from. pulled most all solenoids