So this issue was here when I bought the truck, it just never bothered me because I was at sea level with very few hills. Now I've been back in the mountains several months now and it's getting on my nerves because I'd realy like a longer 3rd gear. Instead it hits 3rd goes right into 4th then ends up having to down shift right away because I'm now going to slow up the hill.

Since the truck purchase my overdrive unit went out, so I have a whole new rebuilt transmission (Jasper). I would like to rule out any internals because of this (gov. pressure solinoid, overdrive valve body ect.) I even had the pan off while the trans was installed and never noticed any shorted or loose wiring.

I've since adjusted the TV cable. It gave me a more crisp 1-2, 2-3 but no change on the 3-4

I tested the TPS with a multimeter and my conclusion was it was good. I replaced it anyway becase a new TPS was $25

So now I am looking at the PCM. I talked to a dealer and It's $85 to re-flash the PCM but I have to drive 2 hours to do so. If the PCM is bad itself will re-flashing it even work or should I be looking for a remaned one? Is there anything else I am missing that could be a culprit?

I am not getting any CEL or codes and the truck runs great otherwise. I've been going off the DIY Transmission Diagnostic in the DIY section

21 - 498 AUTOMATIC TRANSMISSION - 46RE BR/BE
AUTOMATIC TRANSMISSION - 46RE (Continued)
CONDITION POSSIBLE CAUSES CORRECTION
3-4 UPSHIFT OCCURS
IMMEDIATELY AFTER 2-3
SHIFT
1. Overdrive Solenoid Connector or
Wiring Shorted.
1. Test connector and wiring for loose
connections, shorts or ground and repair as
needed.
2. TPS Malfunction. 2. Test TPS and replace as necessary.
Check with DRBT scan tool.
3. PCM Malfunction. 3. Test PCM with DRBT scan tool and
replace controller if faulty.
4. Overdrive Solenoid Malfunction. 4. Replace solenoid.
5. Valve Body Malfunction. 5. Remove, disassemble, clean and inspect
valve body components. Make sure all
valves and plugs slide freely in bores.
Polish valves with crocus cloth if needed.

 

Wonder if the O/D solenoid is just stuck. PCM controls the ground circuit, (brown wire, goes into pin 6 on the trans connector) Need to wire a bulb into that circuit..... (cut the wire, splice some extra length on to it, and hook it to a bulb socket in the truck. or anything that will 'do stuff' when it has current flow.) Go for a ride, light shouldn't come on till you are going 45 MPH. If you get 4th gear, before the light comes on, you have an internal trans problem.

 

Hmmm, okay. So trying to make this easier on myself and find the wire near the PCM. I looked up the PCM diagram, would you be refering to B21 on this diagram?


What kind of bulb should I use? And should I use a specific guage in wire? Also should I disconect the battery before pulling the Wite conector intot he PCM to get a better look at the wiring?

I guess to confirm what your saying..... Could I find the right wire near the PCM add some wire and use something like a tail light bulb and splice it into the extra wire leaving the bulb visable outside my windsheild. Wiring makes me nervous, I guess thats why all the little questions about this test.

 

SO after some conversation with my father what I was feeling was not 3rd gear but was the clutch converter locking up to early. I tested this by accelerating firmly with O/D off, once in third gear keeping my foot in the gas I applyed pressure to the brake. RPM's jump 2-300.

 

Ah, ok, that makes sense. Still, it shouldn't engage until around 45 mph with overdrive enable. (it will engage TCC first, then shortly after, drop into 4th.) If it is hitting it before then, may be able to just get a tuner, and call it a day. (which wouldn't be a bad idea in any event, as you more than likely have the death flash, and the tuner will also get rid of/greatly reduce torque management.)

I think there is a DIY in the FAQ/DIY section to have O/D default to off as well, if you find yourself doing hilly terrain at slower speeds frequently. Turning O/D off moves shift points a bit higher, and a bit firmer.

 

I'm also understanding that this can be corrected by adjusting the TPS. Since the the TPS on this model does not have a slotted bolt holes and can't be adjusted, a tuner seems to be the best option here. Which I'm kinda happy about because tuner is litteraly next on the mod list, I'll prolly email hemifiver by the end of the month

EDIT: I did read the thread on inverting the O/D switch a few weeks ago. I considered it, but just decided to stay stock for the sake or re-sell or trade in. Also I live in hilly terrain but within 1 minute I'm down in the valley with 35-65mph speed limits on the main road through town. Easier to just click it off when I start to climb the passes or head back up hill to my home

 

PCM can be forced to relearn TPS simply by disconnecting the battery for a while. After you hook it back up, turn the key to "on" (not start) count to ten, then start the truck. PCM will relearn TPS, IAC, and a few others.

 

Thanks Hey You. I'll run outside and disconect the battery for the night and give it a shot in the morning.

 

Worked like a charm. Thanks!

 

Awesome.