The truck has about 150k miles on it and had more than one issue from the get-go. It had other codes P1684, P0633, U0168, and P0441 but the others are gone now. I have cleared the codes and the only new one is P0633. It was stalling while driving, and then RPMs hunting and surging in Park, and stalling when I put it in gear. I had to replace a vacuum line from the evap canister in front to the fuel canister (NVLD?) in the back by the gas tank because I found it laying on the engine all MELTED. I thought that might indicate a problematic vacuum leak. 😉
I still have not found where the other end of the other vacuum line from the evap canister is supposed to go, and I can’t find a vacuum diagram for this truck, YET.
— Not to the brake booster. There is a vacuum hose connected from the brake booster to the IAC, which could be wrong, but that is what it is, and I didn’t change it.
— Not to the IAC. (cleaned that.)
— Not to the TPS. (replaced that.)
— Replaced the crankshaft and camshaft sensors. I thought it was interesting the camshaft and crankshaft sensors seem to be identical, but the crankshaft sensor has a 10mm bolt head and the camshaft sensor bolt has a 5/16 head. Both of those are on the passenger side, for anyone who needs to know that. Take the wheel off for easiest access, change them both and throw two spares in the glove box. 🙂 I reckon like a/c and refrigerator capacitors, these are prone to going out on holidays and weekends.
Each one of those replacements individually changed and dramatically improved the symptoms the truck was displaying. While I was changing the crankshaft sensor I found a broken ground strap under there, tucked inside a cross member and replaced that. (Trouble Code: U0168 find and check and clean all the ground points on the vehicle. Find and replace the broken ones, too!)
P0441 The most common cause is the gas cap, which I have not replaced, but that code cleared and never came back after the truck stalled the first time, before I did anything at all, except limp it on home.
Now it is no longer hunting, surging, but I get one spike on the tach gauge about a minute after it starts, (not an actual surge in the RPMs) but it is idling in (P) at 900 rpm and idling in gear at 1100 rpm, staying steady, not stalling, until I take my foot off the brake. Then it just dies. Incidentally, the CEL is also no longer illuminating after I cleared the codes, but this code persists.
P0633 is an odd bird. It has something to do with the SKIM (immobilizer?) code not programmed, but as far as I can tell this truck doesn’t have any kind of antitheft anything on it, and doesn’t have a programmable key. It just has one regular key. And it might need a new ECM/PCU to fix it. :-/
I have read ALL of the following regarding this P0633 Code Meaning :
P 0 6 3 3
(P) OBD-II Diagnostic Powertrain (P) Trouble Code For Engine
(0) Intake Valve Control Solenoid Circuit Low
(6) Fuel Temperature Sensor B Circuit Range/Performance
(3) Injection Pump Fuel Metering Control ‘A’ High (Cam/Rotor/Injector)
(3) Exhaust Gas Recirculation Sensor B Circuit High
Power Steering Pressure (PSP) Switch Malfunction In Key On, Engine Off Self-Test, this DTC indicates the PSP input to the PCM is high. In Key On, Engine Running Self-Test, this DTC indicates that the PSP input did not change state. Steering wheel must be turned during Key On, Engine Running Self-Test PSP switch/shorting bar damaged SIG RTN circuit open PSP circuit open or shorted to SIGRTN PCM damaged.
Is the fuel pump sometimes not priming when you turn the key to ON? (I don’t know! How would I know that?) Start by measuring the fuel pressure and checking whether you have bright white-bluish spark at all four plugs. The mechanical timing is also something that you should check, as we mentioned above.
P0633 OBD-II Diagnostic Powertrain (P) Trouble Code Description
P0633 engine trouble code is about Exhaust Gas Recirculation Sensor B Circuit High.
Main reason for P0633 OBD-II Engine Trouble Code is Fuel Temperature Sensor B Circuit Range/Performance.
P0633 DTC specifically refers to the camshaft (cam) timing. In this case, if the cam timing is over-retarded, the engine light will be illuminated and the code will be set.
— I am going to be replacing the Power Steering hoses because after it sat for some time, I discovered a pretty serious fluid leak there, and I figure I might as well replace all three of them. It needs a new power steering reservoir cap, as well. I thought the one on there was just gunked up, so I went to clean it and it was really difficult to get off, and I discovered it, too had MELTED. How does THIS even happen? The reservoir itself seems to be ok, (knock on wood!). I am hoping the pump is ok as well. And there is NO power steering pressure switch on the high line on this truck. Not even a port for it. I wish. Oh because P0633 can be caused by the Power Steering Pressure Switch on a Dodge Ram. But I guess it has to actually have one for that to be the problem. I am only HOPING that the leaking line and the melted cap could cause the same code. Whether or not they are causing this code, these are things that need to be fixed, so it’s not quite like “just throwing parts at it”.
Some old Dodge guy wrote somewhere, If you own a dodge with a 4.7l that is surging or hunting and have tried all the sensors with no results, try checking the power steering fluid and the power steering fluid pressure sensor. Also: If you have the common dodge 1500 stalling problem. You know, going somewhere between 1-60mph and it stalls while slowing down. Remove the fuel pump plug find the power and ground wires, I think mine where the outside wires on the 4 wire plug. ON TOP OF THE FUEL TANK? (Which I think means removing the bed of the truck because I can’t see mine, much less reach it.) Remove the metal terminals from the plastic plug and bend the tab in the middle of each terminal so that it is closer to the other side (tighter connection around the male end on the pump terminals) also remember to bend the locking tang back out before reinstalling into the plastic plug. If you have enough wire you can buy new terminals and fix them to the wire. Plug back into the fuel pump.
Any other thoughts or suggestions or if anyone has that vacuum diagram MUCH appreciated.
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