2004 4.7L H.O. WJ transmission problem - P0988

[Backwoods Rambler]

Update: I cut the OEM wire and the transmission immediately went into "limp mode" the next time I drove it, but with no CEL. I think there was no CEL because I had the TCM unplugged for 18hours. I assumed that I must not have a good connection with the wire I overlayed to bypass the OEM wire. After checking the connections, I verified that the connection at the TCM was bad. I upgraded the connections at both ends and tested the circuit for continuity. There was continuity.

I plugged everything back in and the transmission is still in "limp mode" with no CEL. Again, I think there was no CEL because I had the TCM unplugged for 18hours.

I double-checked all connections to make sure they were secure. Everything was tight.

I'm thinking my next step is to splice to OEM wire back in and see what happens.

I can't help but wonder if, because I'm using spade connectors and 1 wire size larger than OEM, if I'm adding too much resistance to the circuit? I'll look into that.

 

[deadbeat son]

I can't help but wonder if, because I'm using spade connectors and 1 wire size larger than OEM, if I'm adding too much resistance to the circuit? I'll look into that.

The larger wire will offer less resistance than the OEM wire, perhaps balancing out any signal loss incurred due to the use of the spades.

 

[Backwoods Rambler]

Thank you for the reply. I got it just after this...

Update:

I checked the resistance of the overlayed wire and connections. It came in at 0.5 Ohms. If I'm reading the FSM correctly, anything below 5 is acceptable.

I decided to reconnect the OEM wire with the same spade connectors and run it again. No more "limp mode" or CEL, but I haven't scanned for a code yet.

Interesting thing though. I got continuity with my loop-back wire, when testing the overlayed wire, but no continuity when I reconnected the OEM wire.

I'm checking the wiring in the FSM to see if the OEM wire goes anywhere besides the Transmission and the TCM.