No 1st or OD

[bgreen63366]

I have a 99 Tahoe 4X4 5.7 112xxx. The trans stopped shifting into OD all the sudden. Also noticed there is no 1st gear. I seen a thread on this from last year but no one really addressed it. Any help would be appreciated.

Went to Autozone, here are the codes

P0740
P0753
P0758
P1860

[99 Mob Mobile]

yeah it sounds like your going to need a new tranny.. When they loose gears there pretty much gone.. you can have yours rebuilt..but if its been rebuilt before its kind of a waste of money cause by now the case is worn out

[bgreen63366]

I have also noticed that my gear selection light goes out and my speedo and tach stops working intermittently. The check guages light comes on when this is happening.

[maxwedge]

Care full here, it is possibe this could be a wiring issue, maybe a bad connection somewhere, with the proper wiring diagram and trans diagnostic trouble tree you could check for power to these circuits particulary the trans which may actually be in limp mode as a result.

[2000CAYukon]

Could also be a Shift A Solenoid (also called 1->2 Shift Solenoid) or electrical issue going to that solenoid.

The Shift A Solenoid is ON for 1st and 4th but OFF for 2nd and 3rd.

//2000CAYukon

[bgreen63366]

Yeah, I noticed that one of the codes relates to that solenoid.

[maxwedge]

A scan with a trans function scanner can confirm it's operation.

[bgreen63366]

Where would be a good place to find a scanner like that?

[maxwedge]

Almost every trans shop has/uses this type of scanner.

[bgreen63366]

Excellent, thanks for the help.