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WJ 2001 4.7 codes P0130, P0136, P1491

10K views 15 replies 4 participants last post by  Dlanor82 
#1 ·
P0130 O2 Sensor Circuit (Bank 1 Sensor 1) driver side before CAT
An open or shorted condition detected in the ASD or CNG shutoff relay control ckt.
http://www.obd-codes.com/p0130

P0136 O2 Sensor Circuit Malfunction (Bank 1 Sensor 2) Driver side after CAT
An open or shorted condition detected in the ASD or CNG shutoff relay control ckt.
http://www.obd-codes.com/p0136

P1491 Radiator Fan Control Relay Circuit under PASS headlight
An open or shorted condition detected in the radiator fan control relay control circuit. This includes PWM solid state relays.

So I checked the fuses and wire harness connections on all 4 sensors. look ok.
Found a thread regarding the large wire loom on the right side near the valve covers which can wear on a bolt. That seemed ok.

I don't know where all the grounds are located.

I will try to clean connectors tomorrow.

I was getting a P0601 code so I did just replace the PCM and have not put many miles on it yet. I read the P0601 code blocks other codes from showing up. Once I replaced the PCM the old O2 sensor code showed up again accompanied by the rad fan code.

Could these codes be related in any way or should I just replace sensors? OR since I just replaced the PCM do I need to drive it some more so it has enough cycles? It seems to run a little rougher with the new PCM but I read that will happen until miles are on it after the change. I'm just trying to get it ready to sell. I love the jeep but need better gas mileage for my daily commute.
 
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#3 ·
One part of the output current from the ASD goes through fuse F16 (15A) in the PDC and then on to many other components. Among them are the O2 sensor heaters and the hydraulic cooling module. Your 2001 4.7L uses a hydraulic powered radiator fan and the cooling module is used to control it. So, the answer to your question is yes, there is a connection.

The other part of the of the ASD output goes through fuse F26 (15A), also in the PDC, and then on to the PCM. I don't know for sure how the PCM uses that part of the ASD output.

Assuming that the replacement PCM is specifically for a 2001 and not some other model year, you may need to just put a few more miles on it. Before doing anything else, I think you should replace fuse F26, unless you have used an ohmmeter to check it.
 
#6 ·
hmmm

Other differences would be how many O2 sensors there are (pre1999).
Could my original PCM even throw a 1491 code if there is no rad fan relay sensor to begin with? So if I get a 1491 code now, doesn't that tell me the PCM is not the correct year? It seems like the PCM is telling the fan to go on high not matter what if the AC button is ON when the car starts or if the AC button is turned on once the car is started. Which seems to put a strain on the power steering pump (gets noisy in the cab, but don't hear it much when you are looking under the hood).

If I start the jeep without the AC on the fan is on low and the fan remains on low. doesn't overheat gauge is dead center or slightly less. and the power steering pump makes no noise at all.
Thanks again
 
#7 ·
That P1491 code is most likely available for both the electric fan and the hydraulic fan regardless of the model year of the PCM.

The electric fan uses a PWM signal from the PCM to a PWM solid state relay to control the speed of the electric fan. (This applies to 1999 & 2000 4.7L as well as 1999 - 2003 4.0L)

The hydraulic fan uses a signal from the PCM to the hydraulic cooling module to control the speed of the hydraulic fan. (This applies to 2001 - 2004 4.7L)

Whether electric or hydraulic, the signal comes from the PCM at pin #17 in the connector C2. The wiring diagrams put the label Radiator Fan Relay Control on that pin#17.

I believe that the radiator fan relay control signal is PWM in all cases. There are circuit diagrams which show how the electric fan PWM relay is wired and the operation is clear. It's not clear exactly how a PWM signal to the hydraulic cooling module is used, because circuit diagrams of that module must surely exist somewhere, but do not seem to be available.

Bottom line is that I now think it is very unlikely that the presence or absence of the P1491 code can be used to distinguish between a working 2001 and a working 2000 PCM when the fan is hydraulic. The deciding factor would be whether or not the fan works correctly.

If you haven't done so yet, it might be a good idea to erase the codes and then see if they comeback, especially the P1491.
 
#8 ·
Friend cam by and erased codes with scanner and all codes came right back.

Also the O2 sensors disappear when the battery is disconnected overnight but the 1491 doesn't.

P1491 Radiator Fan Control Relay Circuit- so if there is no relay what am I looking for?

I'm wondering if the powersteering noise is related to the 1491 code?
I did replace as much powersteering fluid as I could using the 5931. Could one of the hoses from the powersteering be bad making the noise.

I'm hoping it's not the pump, it only makes any noise when the fan is engaged in high mode. You can't hear it very much when you're under the hood but you can hear it in the cab and feel a vibration in the steering wheel when turning slowly.

If the AC is not on when the jeep is turned on, no symptoms at all. quiet no vibration and if I leave the AC off and drive, still no noise. As soon as I turn the AC on the fan speeds up and the noise comes from the power steering and it doesn't stop if I turn the AC off again. But turn off the vehicle and start it up with out the AC on and it's fine again.

Thanks again for the help,
I owe you a couple beers
 
#9 ·
Your combination of codes is unusual. At this point I can't think of any relatively simple trouble shooting steps that you can take. It appears that the history of the replacement PCM is somewhat unknown. Because of that and because of the combination of codes, I suspect a faulty PCM is the main problem. About I can do now is recommend that you go to a Jeep dealership where diagnostic equipment could help sort out the possible problems.

Good luck!
 
#11 ·
Hello,

did you ever end up solving the issue? I am in the same boat. I have a 2002 WJ 4.7 HO and just had to replace the PCM. I now have the same codes...
How about that... I too am having this same problem. Where did you get your replacement PCM from? I had to return the PCM I bought from all computer resources because of this problem. The second I fired it up those codes were there. I think it may be a programming error, or something along those lines. I'm waiting for a call back from all computer resources to see what there testing says.
 
#12 ·
Amazing. I just called them this morning. They were very nice and very polite. They said that they would cross ship another unit that would arrive in about 7 to 10 days :(

Did your AC stop working too with the refurb unit? the blower works but the air doesn't blow cold. It was working fine before...
 
#13 ·
Amazing. I just called them this morning. They were very nice and very polite. They said that they would cross ship another unit that would arrive in about 7 to 10 days


Did your AC stop working too with the refurb unit? the blower works but the air doesn't blow cold. It was working fine before...
Yup, blows but not cold. And when I turn it on my radiator fan goes mach speed. And power steering pump whines like crazy. They do have great customer support though. I put my old pcm back in, and none of those codes, just the p0601 and the stalling I had with it. And my air blew cold.
 
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