rollincoal2

I have a '96 12v with the 47re. The trans started slipping in OD a couple months ago. I have since replaced the TC, flushed the fluid and changed filter, replaced all internal solenoids and sensors and today replaced the OD unit and governor press or solenoid and sensor. The truck had been in limp mode and that issue was resolved today but now rather than slipping I have no OD at all. Any help is greatly appreciated.

Robert Rausch

Personally I'd take it to a good trans shop and pay to have them trouble shoot it.

9812vram

My best guess is that you got a bad OD Solenoid right out of the box.

How good are you with a DVM? (Digital Voltage Meter) Pin #6 on the transmission plug (I think it's a brown wire) is the signal wire for OD. I'd hook a jumper wire up to pin #6 and run it into the cab and connect up your DVM. Then go for a boot while monitoring the OD signal. Should see 12v when OD is commanded on ~45-50mph. If you hit 65mph and no 12v, the problem is not with the trans. If you do see 12v but OD does not kick in, we're looking at an internal trans issue. Also check for corrosion or broken wires at the trans plug, that's a common issue for transmission problems.

If Electrical isn't your thing, you can also plug a 100psi gauge into the OD Pressure Test Port. This is located on the driver's side of the trans. Right above the rear cooler line there is a 1/8" pipe-thread plug - this is where your gauge goes. Again, if you hit that 45-50mph and see 0 pressure, OD is not being turned on and now you need to check on the electrical side of things. If you hit those speeds and DO see pressure but no OD, you've got a major hydraulic leak inside, possible a blown OD Piston seal.

If you don't feel comfortable doing these tests, then unfortunately a trans shop is you next stop...

joem

how cold is it where you are? mine wont shift into OD until at least 30 minutes on the road during the winter- gotta love holding up traffic on 70mph freeway sitting at 3,000 rpm in 3rd- I here this is normal though

9812vram

I hadn't thought of that. Good point joem. OD and Torque Lockup are both disabled if trans fluid temperature is below 0*C (32*F). If you let your truck warm up in the morning, it's a good idea to idle it in neutral to help heat up the trans oil quicker...

joem

Mine seems to disable OD even warmer than that, I shot the pan with my IR therometer (spelling) and it was 45F and it still waited for 2 miles to shift up.

9812vram

Yeah, the temp I gave is just the spec. Actual temp will vary from truck to truck depending on the calibration of each temperature sensor. Also, seeing as it runs off voltage varience, resistance differences between wires and pins will also make a difference.

joem

aww, very true! voltage varience sensors are not very accurate- after watching those cash for clunker videos where the rods exit the block before the low oil light comes on!

infidel

Stock it's set to prevent lockup unless the fluid is below 70°F, not 32°.
Even in 0° weather mine will warm up enough to lockup in five miles.
If you try to use a tee for the stock sensor and an aftermarket one on a RH it will take a half hour to warm up enough.
Been there done that.
The tip of the probe needs to be in the fluid flow to read right.

9812vram

My ATSG manual says "When the TFT sensor detects a temperature below 0*C (32*F), overdrive and the torque converter clutch are disabled". At -5*C my truck hits OD and lockup right away with no warm up time. Stock computer and stock Mopar sensor...

It might be different on a 47RH.

joem

yeah must be the RH, today I took mine into town and it was 21F, no warm up- idled down my 1 mile long driveway in 2nd then pulled onto the freeway rated 70, it stayed in 3rd unlocked for 3 miles, then hit OD unlocked for another mile until I hit a small 2% hill then it locked up and I passed everyone that had passed me

high bid

Might want to double ck all grounds. Both batt post, 2 down below the driver batt, 2 on the pass fender and 1 behind the turbo. Im sure theres more but i found these seem to corrode. Keeping these clean will definitely help w/shifting issues.

high bid

Trying to test "no overdrive problem"...So no power at the brown tranny wire means bad PCM?
The no charge and now no overdrive makes me think a portion of the PCM has gone bad. Any help would be appreciated.

patdaly

Not exactly, the 12 volts is always applied to the solenoid, what you are trying to check is to see if that voltage is being brought in by the PCM thru ground. ( PCM grounds both OD and TC LU circuit.)

I believe you said something about a piece of a snap ring in another post, good possibility it is from your OD unit.

I would try manually grounding the OD solenoid and see if it shifts.

high bid

I ran the test yesterday w/a digital volt meter to see if 12+ was coming thru on the wires that lead to the tranny. Sounds like I may of had the "test" backwards. Yes, what looked to be a small snap ring was found. Shifts fine 1-3 and reverse. I've been jacking w/this for a week and ended up taking it to a tran shop close by for them to run diagnostic. I can troubleshoot/repair just about anything but tranny gears and the tranny electronics are not my cup of tea. I did successfully install the transGo kit but that was pushing my limits on tranny knowledge.

Trans shop found codes and were stumped as well
P1389-no automatic shutdown relay output voltage at PCM
P1694-no engine bus message received
P1693-mil fault in companion module

After the alternator conversion (done so it would charge) and bc of the different regulator, I cannot hookup the small two wire plug to the back of the alt...can someone tell me if the wires need 12+, ground, etc or how they communicate with the PCM.