It acts like it's in limp mode, but there are no codes. The speedometer quit and the gear selector was boxed in, along with limp mode. The battery connections were corroded badly. I cleaned them and everything cleared up. The dash gauges are working fine now. Drove it down the road for 25 minutes and it's back in second gear with a hard shift when putting it in gear, but still no codes. Any ideas?

 

Sounds like the wiring. Start with the fuses and relays in the fuse box. Get a diagnostic guide with electrical diagrams so you will be able to trace your wiring.

 

Yeah. That's what I'm thinking, too. I'm going to check all of the grounds and the wiring harness going to the TCM first.

 

I'm not familiar with your particular van construction. Is battery located above the TCM? If it is, that is another reason to check wiring very closely from the relays to the TCM. Just a thought.

 

No codes according to which scan tool?


When you have boxes around all of the PRNDL, it usually means the TCM is off the BUS (no signal present)


Try swapping the K-5 Relay in the TIPM with another one like it, like K-6

 

The boxes went away and the speedometer starter working again after I cleaned the battery terminals. I did swap relays, just in case. When the day gets cooler, I'm going to check the harness wiring for corrosion and shorting. I'm pretty sure I have a bad wire there. When I moved and bent them around, it started working again, then quit. I'm assuming they simply went back to their original remembered position and shorted out again.

 

Yes, it is above the TCM. I'm going to check for shorts there in the next day or two.

 

Your corrosion might even be IN the TIPM connectors. Are you in the salt belt?

 

No. Piedmont North Carolina. Corrosion isn't a big issue, but a wire is bare, it will rust through.

 

TNtech - Don't know why but there's no model year given by the OP. If you go by the bracket on the opening forum page he's in the 4th gen 01-07 range. MikeBruce has an IPM not a TIPM.