47RE Shifting Problem with a Twist

ARbowhunter7

ARbowhunter7

Opulence...I Has It.
Joined
Sep 8, 2007
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I'm fighting the typical 47RE shifting issues that everyone goes through (and has been discussed many a time), but I've hit a snag that's had me cussing and throwing tools for a week.

Little background:
Built, billet 47RE with HTS VB, lockup switch with jumper wire/no trans relay. Drove great 10 days ago.

Speedo went crazy, then died. Truck began taking off in 3rd. I could manually select 2nd but not 1st. Went into OD as usual, with no lockup in any gear. Converter locked fine with my switch, though. Codes showed open circuit in OD/TCC. I replaced OD/TCC solenoid, speed sensors on trans and rear axle, and also put a resistor on orange wire. Nothing changed.

I then replaced governor solenoid and pressure sensor last night, and this is the current behavior (still with dead speedo): Trans still wants to take off in 3rd when gear selector is in "D", but I can now manually select 1st and it works. I can then shift manually to 2nd, then D, then it hits OD normally with no lockup unless I use the switch.

I realize there's a strong possibility that this still is speedometer-related, but I've already swapped the speed sensors to no avail. Anybody have an idea on which direction to go from here?






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stop light switch keeping it from going into lockup?
 
Correct ECM/ PCM in the truck? I had similar issue with one that was bad. Would shift through all the gears, just wouldnt command lock-up.

Have you hooked a scanner to see if it is reading Speed/ Load and Thottle %
 
I'm really hoping it's not that, it did drive fine up until recently.

I haven't had a chance to run a scanner on it yet, but I need to.

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Last edited:
Fix the speedo first as it may be messing with the ABS system if equipped. A buddy had an issue with his trans when the abs was acting up.
 
I know it, I really think they're linked. I've already swapped the two sensors, but still no speedo. From my understanding, there's nothing else that runs the speedometer, though.


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Well, I was under it last night testing all the sensors with a multimeter and I ran across something that seemed strange. I added resistors to the orange wire, pin 31 to get the voltage from 5.2 to around 4.6, but for some reason, on that orange wire, between the resistors and the trans, the voltage is reading only 0.68V, so that's all that the trans is seeing. To test this, I cut the wire immediately after the resistor so that I have the resistor and PCM on one side, and the trans on the other. I checked the resistor/PCM side and got the proper 4.6V. Then I tested the other side, thinking it would read 0.0V, but it read 0.68v. I tested this again, closer to the trans, and got the same number. Why is there voltage coming out of the transmission on the orange wire? As I understood it, the orange wire was a 5v supply to the trans from the PCM?


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Are you touching the leads during testing?

I'm not sure if the circuit will try to do self check diagnostics. It's possible you are seeing pull up voltage from the pcm.
 
I was just sticking a sewing needle through the wire at first, but then tested the leads.

The strange thing is, I'm seeing the same result when testing the complete circuit after I soldered it all together. It's like the trans is shooting that 0.68 voltage back to the PCM, because when the wire is connected, I have 5.2V on the PCM side of the resistor, and 0.68 V on the transmission side of the resistor. I'm sure it's not the resistor, though, because when I cut the wire, I got 4.6V after the resistor, and 0.68 on the other wire (coming from trans).


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Well, I'm clueless at this point. I'm just going to drop it off at Black's Diesel and let Ashley take care of it.


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