Can you post the year and mileage of your JGC? Service history? Last transmission service? Also what transmission is it? NAG1 or 545RFE? I think it's a NAG1 as I don't see the P0730 for the 545RFE.

Probably wouldn't hurt to drop the pan, look at the fluid.

Diagnostic Test
1. CHECK FOR INTERNAL TRANSMISSION PROBLEM

Determine if there are any Transmission mechanical problems present.
Remove the Transmission Oil Pan and inspect for excessive debris or a plugged Transmission Oil Filter. (Refer to 21 - TRANSMISSION/AUTOMATIC - NAG1/FILTER - STANDARD PROCEDURE)

Inspect valve body for foreign material, starting with 3-4 holding valve, and continuing to the other valves.

Is there any Transmission mechanical problems present?

Yes

• Repair as necessary per the Service Information.
• Perform NAG1 TRANSMISSION VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - NAG1 - STANDARD PROCEDURE)

No

• Using the schematics as a guide, check the Transmission Control Module (TCM) pins, terminals, and connectors for corrosion, damage, or terminal push out. Pay particular attention to all power and ground circuits. If no problems are found, replace the TCM per the Service Information. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES/TRANSMISSION CONTROL MODULE - REMOVAL)
• Perform NAG1 TRANSMISSION VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - NAG1 - STANDARD PROCEDURE)

 

Can you post the year and mileage of your JGC? Service history? Last transmission service? Also what transmission is it? NAG1 or 545RFE? I think it's a NAG1 as I don't see the P0730 for the 545RFE.

Probably wouldn't hurt to drop the pan, look at the fluid.

Diagnostic Test
1. CHECK FOR INTERNAL TRANSMISSION PROBLEM

Determine if there are any Transmission mechanical problems present.
Remove the Transmission Oil Pan and inspect for excessive debris or a plugged Transmission Oil Filter. (Refer to 21 - TRANSMISSION/AUTOMATIC - NAG1/FILTER - STANDARD PROCEDURE)

Inspect valve body for foreign material, starting with 3-4 holding valve, and continuing to the other valves.

Is there any Transmission mechanical problems present?

Yes

• Repair as necessary per the Service Information.
• Perform NAG1 TRANSMISSION VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - NAG1 - STANDARD PROCEDURE)

No

• Using the schematics as a guide, check the Transmission Control Module (TCM) pins, terminals, and connectors for corrosion, damage, or terminal push out. Pay particular attention to all power and ground circuits. If no problems are found, replace the TCM per the Service Information. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES/TRANSMISSION CONTROL MODULE - REMOVAL)
• Perform NAG1 TRANSMISSION VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - NAG1 - STANDARD PROCEDURE)

2007 with 197,000 miles on it, no idea when it was last serviced so that would be a good start.
Thanks for the reply, I’ll check it out this weekend. I appreciate your help.

 

So this weekend I replaced the transmission fluid, no change. Changed the filter, no change. Changed the conductor plate and electrical connector, big change…I have no gears at all now. Nothing. Selector glides through just fine, but it never engages a gear. It just sits and revs up to around 2400, then shakes a little bit.
There is a P0743 code, so I’m going to try and change the relevant solenoid (TCC I believe), but before I do…any ideas?

 

Did you get the selector lever connected correctly with the plate when fitting valve block back on ?

 

Yeah, double checked that.
The problem is solved however, turned out to be either dirty solenoid connections on the conductor plate or a broken electrical connector. (The thing with the yellow toggle at the top, with the 7mm bolt inside).
Took it all apart again, cleaned all the connections and then put the old electrical connector back in, and now she runs!

Thanks for the help and direction!