(2000 Durango SLT 5.9L 4x4 155K miles)
Check engine light came on yesterday while towing the boat to the lake. Realized it was starting out VERY sluggish & wouldn't go into O/D. Took me a couple stops to figure out it was starting in 2nd gear and then only shifting into 3rd. Also, it stalled a couple of times at stoplights.
Ran the codes as soon as I got home & checked Chiltons:

P0135-O2 Sensor (Heater circuit Malfunction Bank 1, Sensor 1);
P0753-Shift Solenoid A (Electrical, 37);
P1740-Transmission ????
P1765-Transmission 12 V Supply Relay

QUESTIONS: Are these all related (except maybe the O2 sensor)? Could the shift solenoid or the relay be setting the other codes off?

I am pretty confident my transmission is good-it was replaced at 80K under warranty. Fluid looks great and there are no other transmission-related symptoms.

Appreciate any help!

Lando

 

Were you driving in Over Drive while towing?

 

Welcome to DF
Yes the codes you have are all related. If you loose 12 volt supply, then loose lock-up torque converter(RPM DROP) P1740 and the 3/4 shift solenoid P0753. Your starting point would the P1765 code and go from there.

 

and as hydra is trying to indicate in his post, you should not being towing with OD, you should lock it out (tow haul or OD off button the column shift lever) while towing

 

Thank you!
I'll replace the 12 v relay first...then see if there is more to it.
To answer the towing questions-yes, but only on level or downhill in O/D-my boat is pretty light (no more than 1500# including trailer).
Lando

 

Sounds good as you are below the weight requirement. I was just wondering if you had over heated your trans but all looks well.

 

Now, only code 0753 remains...but still no 1st & O/D. Replaced shift solenoid & pressure transducer, filter & fluid.
Any other suggestions??

Lando

 

Code P0753 is a 3/4 shift solenoid. Thats not a governor. Get a price on a reman valve body.

 

While trying to remove the old & install the new plug for the solenoid overdrive lockup, I had to remove the cylindrical piece on the driver's side of the valve body-inside it there is a heavy duty 3 inch spring...it was broken!
What is this piece called so I know how to reorder? I'm thinking this had to do with why I wasn't shifting into overdrive??
Appreciate the help.
Lando

 

OK, found the part-it's a whopping $2 online.
Could this be the culprit or do you thinking it's bigger than that??
Lando