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 Chris (aka-Moose) Your Own Question
Chris (aka-Moose)
Chris (aka-Moose), GMC Technician
Category: GMC
Satisfied Customers: 43882
Experience:  16 years of experience
Type Your GMC Question Here...
Chris (aka-Moose) is online now
A new question is answered every 9 seconds

I have a 1999 Denali and the trans is only going into second

Customer Question

I have a 1999 Denali and the trans is only going into second and third gear and reverse my check engine light is on and I got it scan and 3 codes came back
Submitted: 7 months ago.
Category: GMC
Expert:  Gary replied 7 months ago.

can you tell me the code numbers set ?

Customer: replied 7 months ago.
P0740. P0748. P1122. P1810
Expert:  Gary replied 7 months ago.

any access to a multi meter ?

Customer: replied 7 months ago.
Expert:  Gary replied 7 months ago.

start it up and when its acting up and the truck running how many volts are at fuse # ***** called TRANS in the inside fuse box ?

Customer: replied 7 months ago.
It's a 10 amp fuse in number 20 and it's says prndl
Customer: replied 7 months ago.
It read 12.34 volt
Customer: replied 7 months ago.
Is there another fuse box in the truck beside in the driver jam
Expert:  Gary replied 7 months ago.

that is the fuse box

it should be a fuse called trans

Customer: replied 7 months ago.
Here's a pic
Customer: replied 7 months ago.
Did you get the picture I sent
Expert:  Gary replied 7 months ago.

can you unplug the big round transmission connector and with the key ON does the pink wire in that connector show 12 volts ?

Customer: replied 7 months ago.
Where is this connector
Expert:  Gary replied 7 months ago.

passenger front near where the cooler lines connect to the transmission

Expert:  Gary replied 7 months ago.

let me know i have to step out for a few hours i will respond back as soon as i get back

Customer: replied 7 months ago.
Hi I looked all over for that plug n I can't find it can u get me more details on where it is
Customer: replied 7 months ago.
Now I have codes P0713 P0740 P0785 P1860 2nd n 3rd are strong and reverse is strong also
Expert:  Chris (aka-Moose) replied 7 months ago.

Welcome, I'm Chris (aka Moose). I normally log in after 3 pm central. Please make sure to let me know exactly what is needed from me so I can provide EXCELLENT 5 STAR service.

  1. The previous tech has opted out, would you like me to try?
Customer: replied 7 months ago.
Expert:  Chris (aka-Moose) replied 7 months ago.

Great, do you want the GM diag steps for these codes or my thoughts on what is to blame without diag?

Customer: replied 7 months ago.
What's your thoughts I been reading a lot about it and it seems to be stuck in limp mode but when I clear the codes they come rite back . before this happen the trans pan gasket was leaking so the fluid was low so I changed the gasket n fluid n shift solenoid s
Expert:  Chris (aka-Moose) replied 7 months ago.

Thanks, ***** ***** alot of electrical codes for the transmission. I believe your going to find a possible wire or connector issue at or in the trans. ON the trans is a 13 wire connector, can you unplug it and check the connector and pins. Confirm the black wire is a good ground. Confirm the pink wire is power with the key on. If all is good then we need to follow a pinpoint test.


On your screen you should see a rating 1-5 stars. Please make sure to select one. I am not compensated by the website unless a customer rates. Rating only pays me from the deposit you have already made, it does not charge you more, nor close the post. Also all follow ups are free and welcome.

Thanks Chris

Customer: replied 6 months ago.
I haven't had a chance to check out the truck with the holiday n all but I hope tomorrow or mid week
Expert:  Chris (aka-Moose) replied 6 months ago.

Thanks for the update.

Related GMC Questions