-47RE, Automatic, some common troubles & fixes
Howdy, after working through some basic issues with the electrical control of my 1998 47RE Automatic transmission I found some very helpful information in TDR but it was scattered all over in old posts so I decided to compile some helpful information to hopefully make your truck perform as it should and a lot less hassle on your part looking for information.
I am going to click and paste other people’s great posts into this post to speed things up; I am no way taking credit for them just passing along the info to the family at TDR. By all means please add to this to make it better.
-TPS, “throttle position sensor” it is a very important part of the puzzle, bottom line it needs to provide the right voltage from the idle position to full throttle any quirks, going open or jumping in voltage in the stroke and you’re going to have problems it needs to be smooth a good OHM/Volt meter is your friend.
You can by a new one or drill 2, 1/8 holes on the face at 12 & 6 load it with wd-40 cycle the switch in your hand do this “many, many” times, plug the harness back into the TPS while in your hands turn the key on and with a pair of needle nose pliers from the back rotate it with your meter connected and watch the voltage, it will start at roughly .2V and go to almost 3V it will go open above 3V, “meter will get lost for a second” then read 5.12 volts or close to that twisted wide open, as long as its smooth with no hiccups over and over I say run it, my used original did this, I had read the tech bulletin below and assumed it was bad so I bought a new one from Dodge, $185 later it metered exactly the same as the used one…my used one is on the truck now is set about .8V at idle and man are my holes hogged out to rotate it that far! And I get 2.98V at full throttle, so far the trans seems happy now and is shifting right.
-TPS Adjustment
The throttle position sensor, shift lever, and throttle valve cable are critical to proper operation of the transmission. If one or more of these are out of adjustment or if the TPS is noisy, shifting will be erratic. Before performing any adjustments, check the transmission fluid level and sniff the fluid. Do not make any adjustments until the fluid level is correct, and burned fluid has been replaced.
The service manual says to adjust for 0.8-1.2V at idle. On many trucks, this voltage is too low, resulting in TCC chatter at moderate throttle loads. The TPS is not officially adjustable but the mounting holes are slotted and the body can be rotated slightly. Adjustment is relatively easy, and requires only a digital voltmeter and a few hand tools. A little adjustment goes a long way...
TPS wire color code:
· Black = ground
· Orange/dark blue stripe (center pin) = signal
· Purple/white stripe = 5V power
Testing and adjusting the TPS:
1. With the key "OFF", unplug the connector from the TPS.
2. Turn the key "on" and insert DVM probes into the connector to reach the connector pins. Short pieces of wire or paper clips can be used to extend the DVM probes for reaching into the connectors.
3. Read from the purple wire to the black wire (these should be the outside pins). Power should be 5V with the key "on".
4. Turn the key "off" and plug the connector back onto the TPS
5. Insert the leads from the digital volt meter into the back of the TPS connector. The DVM negative probe goes into the back of the connector cavity with the black wire. The positive DVM probe goes into the back of the connector cavity with the orange signal wire.
NOTE: Push the probes into the rear of the connector until the probe tips reach the metal connector pins.
6. Loosen the TPS mounting screws
7. With the engine off and key on: Adjust the TPS position for 1.2 to 1.5V on the signal wire with the throttle at the idle position - more voltage makes more TC clutch pressure, too much will set a fault code. Often, adjusting for 1.4 to 1.5V at idle will cure TC clutch chatter under light load conditions. NOTE: The factory setting is 1.2V max, so proceed carefully.
8. Tighten the TPS screws, slowly open the throttle to the WOT position and then return to idle. Watch for voltage jumps - the voltage should change smoothly from the idle value to at least 3.5V at WOT (5 volts is all you should be able to get). If the sensor voltage jumps or drops unexpectedly - replace the sensor or try the filter modification below.
Posted to a TPS thread on the TDRoundtable by Bill Kondolay (Bill is one the true transmission experts out there):
Note: I did some minor editing to put it into the context of this web page - Dave.
Before anyone follows advice on how to adjust the TPS keep in mind that every action has a reaction. You can adjust the TPS voltage to pretty much whatever you want without following Chrysler’s procedures. Before starting, always record your original idle voltage; you must have a baseline to start from.
Make adjustments in small increments. First remove the TPS, knock out the 2 steel sleeves, with a small file oblong the holes;”More like hog out the holes with a drill bit to get enough room to rotate it for the right voltage”, and install the tps sensor. Always start with the original voltage you had; as you increase your voltage your OD and TCC lock up will start to come in later and later. The down side of doing this is that when you slow down or if you remove your foot from the throttle, the TCC will not unlock unless you step on the brake pedal or your vehicle speed drops below a certain setting.
TPS Filter Construction - Bring a dead TPS back to life
Steve Clayton
Gemcuttr1@cs.com sent this simple technique for filtering the output of a noisy TPS.
I did some experimenting and found that an electrolytic capacitor (440 microFarads, 35 Vdc) with the negative side connected to the SIG RETURN wire and the positive side hooked to the TPS SIG wire gave me absolutely *trouble free* operation! Even though my TPS is basically trashed, the capacitor filters out almost all of the electrical noise, and my auto tranny once again shifts like factory-new!
I dug into the wire bundle coming out of the PCM and soldered the capacitor as close to the plug as I could manage - thinking some "TPS problems" may actually be wiring/connector problems in disguise.
Results with other values were:
· 220 mF, 35 Vdc - too little filtering. Tranny a little flaky.
· 1000 mF, 35 Vdc - far too much filtering, and a 1.5 second delay in transmission shift response crept in.
BTW, I might add that since I added the capacitor, my cruise control hasn't dropped out even once in 15K miles - usually a twice-per-week occurence (I drive 1500 miles a week). What I believe is that the dropout problem is caused by an electrical noise spike from the TPS - which is *exactly* what the capacitor filters out.
Please consider this tip a free gift for oilburner fans! The capacitor costs just 40 cents, and I hope it will save TDR members and others lots of money! After all, you can by a lot of #2 diesel for $200! :-
Linear Mode
