P1482 Code- AFTER replacing Clutch fan

[Mike]

For starters, I owe a 'thank you' to [somebody] for directing me over here from the other forum. As a mod/admin of a drum builders forum, I have had to deal with the same thing. It sucks but, its bound to happen.

You guys helped me a months ago with a noisy cooling fan. I replaced the fan/clutch assembly. After doing so, the check engine light has been on. I check the code (getting P1482) and reset it. The light usually comes back on within 3-4 starts of the vehicle. The new fan works but the CE light is on and I keep failing my emmissions test.

I followed a troubleshooting guide I found back that the other forum but that didnt solve me problems. I can send 12v directly to the clutch and get the fan to 100%. Remove 12v and it releases. I'm totally lost. There are no other issues that I'm aware of. I would greatly appreciate any help or advise!

 

[Ace1875]

For starters, I owe a 'thank you' to [somebody]for directing me over here from the other forum. As a mod/admin of a drum builders forum, I have had to deal with the same thing. It sucks but, its bound to happen.

You guys helped me a months ago with a noisy cooling fan. I replaced the fan/clutch assembly. After doing so, the check engine light has been on. I check the code (getting P1482) and reset it. The light usually comes back on within 3-4 starts of the vehicle. The new fan works but the CE light is on and I keep failing my emmissions test.

I followed a troubleshooting guide I found back that the other forum but that didnt solve me problems. I can send 12v directly to the clutch and get the fan to 100%. Remove 12v and it releases. I'm totally lost. There are no other issues that I'm aware of. I would greatly appreciate any help or advise!

Welcome Mike,

i would suggest putting a MM on the fuse number 20 & switch out relay number 45. check and see if you have 12v in there. its a start. usually a drop in voltage means a short or a bad relay. swtich out the relay with the HDM low beam relay and see if it helps.
EDIT MAY03LT has a video of how to diagnose a bad relay.

[video=youtube;et7KJi76iHk]http://www.youtube.com/watch?v=et7KJi76iHk[/video]

 

[The_Roadie]

Hiya, Mike. That was my invitation, but prying eyes from the other site would love to ban any username that's trying to educate trailvoy members as to the truth of what went down in December. So I edited it out.

That code is involved a diagnostic of the PCM's control signal TO the relay having a short to ground or an open. So your problem is on the input side of the relay. Might be a bad relay or it might be a flaky wire between the PCM and the relay, or a bad connector on either side of the circuit. Your new fan spins, but that could be due to residual friction in the clutch. The real test is if the fan spins up to full engine RPM when it's over 220 degrees, which is hard to manage except towing in the summer up a long hill. A mechanic with a good enough scan tool can command the fan to do its thing, or a dealer, but mostly we shun the dealers unless we're hosed. You did the right thing testing the clutch function with a jumper.

Upper right of this schematic:

 

[Mike]

Thanks for the reply, Ace!
I swapped the relays and no difference. The headlights worked with the relay swap. When I put a jumper between the #2 and #4 slots after pulling relay, the fan reaches 100%. When I pull the jumper it drops back to what I would call normal.

I'm wondering if there's a communication issue between the trucks CPU and the relay. What kind of voltage should I get on the coil side of the relay? Could there be a problem between the CPU and relay?

 

[The_Roadie]

I'm wondering if there's a communication issue between the trucks CPU and the relay.

Precisely.

What kind of voltage should I get on the coil side of the relay?

It's a PWM signal, if you've heard that term. I think the high would be 12V. Low is ground. You can look at it with an oscilloscope, or a meter on AC will read the average. But if the PCM isn't commanding full fan RPM, the average is going to be low.

Could there be a problem between the CPU and relay?

That's it. Inspect the wiring and the connectors, then check continuity. Might be underneath in the fuse block.

 

[Mike]

Thanks Roadie! After I made my post I thought about editing the UN.

Unfortunately I don't have a good enough scanner to try commanding the fan. My father in law has a beastly looking scanner. Maybe ill try his. Until then, is there any way to check voltages or communication from PCM?

Edit.... I'm posting from. Mobile phone.... I didn't see the rest of your post about PCM voltage before responding. So I guess ill need to remove the fuse block and look for and trace wires?

 

[The_Roadie]

You can pull the relay and look with a meter at pin 5 of its socket. Without a pull-up resistor I think is contained in the relay, it may not be a good diagnostic test. You can wrap a tiny wire around the blade of the relay pin 5 and stick it BACK in the socket and look with a meter on DC and AC, but the right tool for the job is an oscilloscope. Or pull the PCM connectors, and figure out which one is C1, pin 57, and then check continuity to the relay socket. Or you might find flakiness/corrosion/crud on the PCM connectors when you take them off and some contact cleaner spray might fix it up.

 

[Mike]

is there any chance all of this is related to the O2 sensors? my wife showed me the report from the emmissions test and it indicates something to the effect that the failure is due to P0420 code. I tried two different code readers and they're saying P1482. I ordered to O2 sensors. They'll be here tomorrow. Any chance the two are related?

 

[Mike]

Ok, short of unleashing my new AR15 on this PIA TB, I decided to give it one more go... I started with the easy stuff and think I've found the problem. I was checking the #20 fuse when I noticed it was loose. Did some voltage and continuity tests and found that the contact the fuse was making was not good. I figure everytime she (the wife) hit a bump it rattled the fuse enough to break contact. Like the typical half-asser that I am, I twisted the fuse prongs a little to where it was TIGHT in the socket. Reset the code and after 20 start-ups, no problem. I even had a mechanic friend tell me that the Dorman fan I installed was junk. I'm crossing my fingers.........

 

[Mike]

after replacing the cat, i have not had any trouble. i still dont understand how a 1482 code popped up with a bad cat but, its fixed and good to go....

 

[filthyfingers]

Thanks I’ll recheck fuse 20 and the holder