How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask frank Your Own Question
frank
frank, Chevrolet Technician
Category: Chevy
Satisfied Customers: 3420
Experience:  33 years experience,24 years of Chevroler/GM experience and training .ASE Recertified Master Tech,
1816887
Type Your Chevy Question Here...
frank is online now
A new question is answered every 9 seconds

IVE GOT A CODE PO785 HOW DO I FIX IT MY PROBLEM IS 97 ...

Customer Question

IVE GOT A CODE PO785 HOW DO I FIX IT? MY PROBLEM IS 97 S-10 BLAZER TAKES OFF IN LIKE 2ND GEAR AND I DONT HAVE OVERDRIVE, STAYS IN 3RD
Submitted: 10 years ago.
Category: Chevy
Expert:  frank replied 10 years ago.

Make sure that all the fuses in the drivers side fuse box are hot. Do you have reverse?

Customer: replied 10 years ago.
YES I HAVE REVERSE, ILL CHECK ALL THE FUSES BUT I THINK THEYLL BE OK, BECAUSE LAST NIGHT I REPLACED THE 2 SHIFT SOLENOIDS AND RESET THE COMPUTER AND ITDROVE PERFECT FOR 5-10 MIN. THEN BACK TO THIS PROBLEM AGAIN. I NOTICED THAT IT DOESNT DOWN SHIFT WHEN COASTING TAC GOES DOWN TO 700 AS IF YOU PUT IT IN NEUTRAL, IT ACTS LIKE YOUR TAKING OFF IN 2 OR 3 GEAR INSTEAD OF 1ST AND WHEN AT 55- 60 MPH, TAC IS AT LIKE 3000 RPM. I KNOW IT SHOULD BE IN O.D BUT WHEN IM GOING 55 I WATCH THE TAC AND SHIFT TO 3RD AND THE TAC DOESNT CHANGE SO I KNOW IM ALWAYS IN 3RD AT HIGHER SPEEDS, WONT GO INTO O.D. IM GETTING LIKE 11- 12MPG RIGHT NOW.
THIS MORNING IT WAS 3 DEGREES OUT AND I STARTED IT TO WARM UP, WHEN I LEFT, THE TRANS WORKED PERFECT AGAIN BUT WHEN RESET LIGHT IT CAME RIGHT BACK ON AGAIN.
Expert:  frank replied 10 years ago.
As soon as the fault occurs and the code sets the computer locks out the shift- so cycling the key may make it work but clearing the code will make it work. It does sound like a shift solenoid in how it faults.Mine did the same thing but intemittently for a year till I could find it and it was the shift solenoids. I'll have to print the trans connector so you could ohm out the circuit at the connector with out droping the pan again- you could have a short inside in the harness but the igniton switchs has a problem of droping power. The ip fuse feeds the trans.
Customer: replied 10 years ago.
ARE YOU SAYING BY RESETING THE COMPUTER WITH MY SCANNER, AND CYCLING THE KEY, IT SHOULD SOLVE MY PROBLEM? AND IF SO, HOW MANY TIMES SHOULD I CYCLE THE KEY? YOU MEAN ON/OFF SEVERAL TIMES RIGHT? I JUST REPLACED BOTH SHIFT SOLENOIDS LAST NIGHT.WITH MY SCANNER HOOKED UP WITH RUNNING, IF I RESET THE CODE, DRIVES NORMAL BUT WITHIN A MIN, LIGHT COMES BACK ON AND BACK TO PROBLEM AGAIN. I CHECKED FUSES IN DRIVERS SIDE, ALL HOT. AND I TRIED TO CYCLE KEY BUT DONT KNOW IF I DID IT CORRECTLY.
Expert:  frank replied 10 years ago.
No- I am saying that when the fault occurs the trans will go into default until you cycle the key or clear the code.
Customer: replied 10 years ago.
OK, SO HOW DO I FIX IT, KEEP IN MIND I PUT IN NEW SHIFT SOLENOIDS.
Expert:  frank replied 10 years ago.
Go back and read my post 2 back.
Customer: replied 10 years ago.
SO AM I WAITING FOR YOU TO PRINT THE CONNECTOR, AND ARE YOU SAYING ITS POSSIBLE MY IGNITION SWITCH IS MY PROBLEM. THIS IS MY FIRST TIME USING THIS SERVICE SO DONT GET FRUSTERATED I DONT KNOW HOW THIS WORKS.
Expert:  frank replied 10 years ago.
I sent you 8 pages of diag and schematics to your e-mail
Customer: replied 10 years ago.
Reply to frank's Post: HEY FRANK, I JUST REPLACED THE WIRE HARNESS THAT GOES INTO THE TRANS. THOUGHT THAT WOULD CURE PROBLEM BUT IT DIDNT. I GUESS THE NEXT THING TO DO IS CHECK AT THE CONECTOR ON VEH SIDE FOR VOLTAGE PROBLEMS? HOW DO I KNOW WHAT TO DO IF THERE IS A VOLTAGE PROBLEM THERE. IS MY VCM BAD IF THERE IS PROBLEMS THERE? AND IF SO, WHAT DOES ONE OF THEM COST APROX?
Expert:  frank replied 10 years ago.
The flow chart that I sent you has all the diag that you need.You need a scanner that can command the solenoid or ohm out each wire. Follow the chart -no short cuts- and you'll fix it.Get a test terminal,the male and female and check for propper tention on the car with them,you may have a loose terminal.PCMs run about $350 but the dealer has to program it and the theft deterent.