Code 542 need help understanding
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Senior User
Joined: Feb 2016
Posts: 125
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From: Kingsport TN
Code 542 need help understanding
Well fun begins again
Short version of long story. Replaced tank and fuel sending unitm .No problems .Ran fine put gas in tank switched to front tank ran for 1 minute went to leave pump died out. Switched to back tank started ran fine.
Got home started checking out to find problem .Found that the switch did not have power to the tank .Replaced switch. Same problem.
Reran tests still no lower to front tank at switck
I still have some tests to run. But I decided to run codes..
I got the following results:
KOÈO 111
CM 334 337 542
Did not run any more tests figured I'd fix these problems first.
Broke vac line so replacing them
But 542 fuel pump secondary circuit fault . Have not tested anything else yet working on vac replacement first. Since did not know much about the code did research.
Can someone explain this better .The subject is really confusing. Will bad pump throw this code? That's what I think it is but haven't tested to prove it yet.
I would like to understand code better before I waste time doing unnecessary tests.
Any and all help greatly appreciated.
Thanks
Charlie
Short version of long story. Replaced tank and fuel sending unitm .No problems .Ran fine put gas in tank switched to front tank ran for 1 minute went to leave pump died out. Switched to back tank started ran fine.
Got home started checking out to find problem .Found that the switch did not have power to the tank .Replaced switch. Same problem.
Reran tests still no lower to front tank at switck
I still have some tests to run. But I decided to run codes..
I got the following results:
KOÈO 111
CM 334 337 542
Did not run any more tests figured I'd fix these problems first.
Broke vac line so replacing them
But 542 fuel pump secondary circuit fault . Have not tested anything else yet working on vac replacement first. Since did not know much about the code did research.
Can someone explain this better .The subject is really confusing. Will bad pump throw this code? That's what I think it is but haven't tested to prove it yet.
I would like to understand code better before I waste time doing unnecessary tests.
Any and all help greatly appreciated.
Thanks
Charlie
Lead Driver
Joined: Jul 2007
Posts: 7,868
Likes: 9
From: Rhode Island
It's saying the computer is not detecting power on the secondary fuel pump circuit. So if you have a fault with the switch or fuel pump wiring, the computer will not detect power at the pump and set the code.
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Senior User
Joined: Feb 2016
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From: Kingsport TN
That makes sense. I think what bothers me is the phrasing secondary circuit. Makes it seem more intimidating.
I am still working on the vac system lines. So I haven't started retesting the fuel circuitry. I think it's gonna mean dropping the tank again. I really don't want to do that but it is what it is. I'm fairly certain the pump wet out.
I stepped back just to clear my head out. Then tackle the problem again. I know that I have to clear all the codes any way so...... Might as well fix the other codes first. Gotta do it anyways.
Thanks for the reply it helps to see it put in someone's else's words. Kinda clarifies it. If you know what I mean. At least the pomp etc is under warranty. If that is what turns out to be the problem.
Thanks
Charlie
I am still working on the vac system lines. So I haven't started retesting the fuel circuitry. I think it's gonna mean dropping the tank again. I really don't want to do that but it is what it is. I'm fairly certain the pump wet out.
I stepped back just to clear my head out. Then tackle the problem again. I know that I have to clear all the codes any way so...... Might as well fix the other codes first. Gotta do it anyways.
Thanks for the reply it helps to see it put in someone's else's words. Kinda clarifies it. If you know what I mean. At least the pomp etc is under warranty. If that is what turns out to be the problem.
Thanks
Charlie
Fleet Owner
Joined: Aug 2005
Posts: 23,667
Likes: 301
From: Easton,Ks
Do not worry about this code at this point. It comes up when working with the electrical in the fuel system and stays for about 60 or 80 start ups unless you clear the codes.
So clear the codes and worry about it if it comes back up in CM.
Sounds like you may have a bad plug that plugs on to the selector switch or open wire going to the fuel pump that has no power.
So clear the codes and worry about it if it comes back up in CM.
Sounds like you may have a bad plug that plugs on to the selector switch or open wire going to the fuel pump that has no power.
Thread Starter
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Senior User
Joined: Feb 2016
Posts: 125
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From: Kingsport TN
Thanks subford.
I'm not too familiar with emissions. Never really had to play with it much .
I did check the pump for continuity and got nothing. If I am correct I should get continuity thru the pump.
That should tell me that the pump may be bad. Next thing I'm thinking is to check continuity of the power and ground to the plug. If that's there then the 542 may be coming from the pump
I'll update once I play with it,
Thanks again
Charlie
I'm not too familiar with emissions. Never really had to play with it much .
I did check the pump for continuity and got nothing. If I am correct I should get continuity thru the pump.
That should tell me that the pump may be bad. Next thing I'm thinking is to check continuity of the power and ground to the plug. If that's there then the 542 may be coming from the pump
I'll update once I play with it,
Thanks again
Charlie
Thread Starter
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Senior User
Joined: Feb 2016
Posts: 125
Likes: 0
From: Kingsport TN
Alright fixed codes in cm excopt for 542. Now I get in CM. Only when I switch to front tank checked circuits have continuity with switch flipped to front none with switch set to back tank. Pretty sure it is pump. Gotta drop tank only went 83 more on new tank and sending unit.got new coming in. Thanks for all help
Charlie
Charlie
Trending Topics
4wd High
Joined: Jun 2020
Posts: 9
Likes: 0
code 542 92 explorer
What was the fix for this? I only have one tank on a 92 explorer and am getting this code.
Engine starts runs but when giving it gas it goes up and down in rpm, sometimes tac stops working But eventually giving it gas again will start it working.
I am leaning towards injectors maybe one bad one that may short under load?? It has 567,000 miles on it.
Engine starts runs but when giving it gas it goes up and down in rpm, sometimes tac stops working But eventually giving it gas again will start it working.
I am leaning towards injectors maybe one bad one that may short under load?? It has 567,000 miles on it.
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