My truck just hit 150k miles and until now I haven’t had any problems that I couldn’t figure out. I got a P0551 code on it last spring which is the power steering pressure sensor. I replaced it and was good to go. About 2 months later, the truck stalls and the cel comes on after starting it up again. This time it has P0442 evap emission system leak, P0320 crank sensor, and the P0551 power steering pressure sensor again. I replace the 2 sensors and replaced the purge solenoid and everything was good to go.
About a month later, the cel comes on and the truck starts running really rough. I get the code P0601. The PCM. So I replace it and the battery and again, I thought it was good to go. A week goes by and the cel comes on again. It’s P0551 again! This time I say screw it and ignore it because the truck seemed to be running fine. I know, probably not the best idea.
Anyway, the cel turns off and on randomly for a couple of weeks and then it starts having a starting issue. It’s intermittent where as sometimes it fires right up and then sometimes it takes me about 5 turns of the key to get it to even try to start. I thought maybe it’s the ignition switch but I kind of procrastinated on this issue and haven’t really looked at it. Not sure if this is relevant to the new problem. This has been going on for a week or so.
So 2 days ago, the truck stalls at a red light. I crank it up and the cel comes on again. I hit the gas and yep, it starts the same erratic behavior as before. I check the codes and I have the same 3 as before. P0442, P0320, P0551, and a new P0725 which is the engine speed sensor. My question is what could be causing these same codes and problems? It seems like replacing the sensor is fixing the symptom rather than the problem. Surely, I’ll be getting the P0661 soon and have to replace the expensive PCM again. Any input will be greatly appreciated. I’m thinking I might be in over my head on this one though.
Thanks in advance!

 

Where did you get your last pcm from? Have you checked you wiring?

 

Just a thought on the P0551, maybe there's a problem with the power steering and not the sensor. Too high a pressure and it can trip the sensor.

Disconnect the battery. The pull all 3 connectors on the PCM. A common problem with the power steering switch failing is that fluid leaks through the harness into the connector and PCM.

There's a good chance the P0320 and P0725 codes are caused by the same item, likely the crankshaft position sensor. The P0725 results when the transmission control module doesn't get the speed signal from the engine. The crankshaft position sensor can account for the difficult starting too.

 

I bought the pcm from Auto computer exchange.com. As far as wiring, that was gonna be my next step. They all looked good but I know I need to check them with a mulitimeter. Which I will have to learn how to do. lol. I'm definitely not a great mechanic.

I'm just trying to gather all possible or likely causes so I can determine if it's something I can actually fix. The fixes I see from the codes are to replace defective sensors, connectors, or wires. Which I think I can handle. Also, It says that the fuel cap could be defective for the P0442. I'll just replace it to make sure. But other than that, could there be something else that could be causing the same set of codes? I seen on another forum about flushing the power steering fluid. I did drain it and replace the fluid the first time I changed out the pressure sensor but I don't know if that's good enough or heck, I might of messed it up then. Thanks or the quick reply!

 

thanks 00DAN! I'll pull that now and check it out.

 

Pulled the pcm connectors. there is some fluid in one of them. I pulled the engine shroud off the bottom found power steering fluid on the wires and dripping onto the top of the shroud. Thinking the power steering switch is definitely bad. Am I gonna have to replace all of the wiring and connectors too? And do you think replacing the power steering pump would stop the power steering switch from breaking. This is the 3rd one in about 6 months.

Tomorrow, I will replace the crankshaft sensor again and check the wiring. Also the thing I got from auto zone says to check the trigger wheel. That may be above my skill level though. Actually, after a quick google check, I'm pretty sure I shouldn't be messing with that thing. lol. I really hope that is not the problem. But if it is, could that be what's causing the starting issue? I'm gonna also check the starter wires and stuff tomorrow. A guy at work said that it could just be a loose wire. Yeah right. That'd be too easy.

 

Check the switch to see if it is still leaking then get some electrical cleaner and spray the connectors at the PCM. You'll have to do it a few times. Replacing the harness is probably not necessary but it will take time for the oil to work its way out of the harness.

I tend to think you have a pressure problem and are "blowing" the switches. It could be a bad relief valve in the pump. You can test the pump output pressure. 1450 psi is the max for the system.

The trigger wheel, tone ring, is in the engine on a 4.7. Don't worry about it. Some engines, the 5.9 for example, the tone wheel is part of the flexplate and can get damaged.

Often, the P/S fluid causes all sorts of weird gremlins. You may even find it at your O2 sensors.

 

Ok. Thanks! I really appreciate the help! I'll update this tomorrow after I see what I can figure out. Or break. haha.

 

Ok, so I cleaned all of the electrical connectors, replaced the crankshaft sensor, replaced the drivebelt since it was looking a little worn, the power steering pressure sensor, and decided to replace the power steering pump.

Now I have a new problem. Go the pump from auto zone and after putting it all together, it is whining real loud. I continued to bleed the system and it helped some but it is still pretty loud. My questions now are, did I get a bad pump? or could I have possibly messed something up putting it together? or is there anything else that could cause this? ie., the power steering fluid cooler or a damaged line or ??

 

never mind. I'm an idiot. I still have air in the system.