Code 542 question

roadfever2

Registered User
My car - a 1994 SC automatic - turns over but does not start. This happened once and I let it sit over night. It started in the morning and I ran it for a day. Next day after running it for an hour I turned it off and it hasnt started since. I had a friend check codes at his shop and we got a code 542 - Fuel pump secondary circuit failure: EEC to ground. Can anyone help me here? It sounds like a bad ground soemwhere but I have no idea where to start looking. What components are in the fuel pump secondary circuit (e.i. relays, switchs. etc.). Does anyone have a decent wiring diagram that could be emailed to me?

Any help here would be greatly appreciated!

Thanks

Jon

roadfever2@aol.com
 
code 542

You can start by cheking the conecting plug to fuel pump and check for dirt in the plug itself in the trunk driver side quarter panel. Also check the ground conections in the wire harnes in the engine compartment. I had the same problem and cleaned up all ground conections and fixed the problem. Good luck!.
 
Thanks Hector
For some reason she started and ran long enough to get her home (about 25 miles). Ran fine. I turned it on and off a few times and cleaned the grounds in the engine compartment as well as the one by the EEC behind the kick panel and cleaned all of the connectors except the one on top of the tank. Wont start now. Im checking the circuit with a multimeter (trying anyway - not real savy with the tool). I thought it may be the fuel pump but or the connector on top but if that were the case, it wouldnt continue running after it starts?

Only time will tell :~)

Jon
 
code 542

You can also check or replace the fuel pump relay some times when there on the way out they actup. Make sure you check the one on driver side quarter panel in the trunk behind the rug. Good luck! .
 
I looked back there for the relay the other day - nothing. Upon further investigation, I learned that the 1994 model (possibly 1995 as well) has the relay inside the IRCM behind the right headlight.
I dont think thats the problem though. I just unplugged the inertia switch and connected the red lead of my volt meter to the pink/black (coming from the EEC/IRCM) wire inside the pigtail and grounded the other lead. I get 9.2 volts. I havent checked the inertia switch yet but I used a spare that I have so I doubt that it either - I will check that as well. The switch is in the reset position. My best theory is the ground between the pump (top of the tank) and wherever it ends up. Or the pump itself which I can check when I drop the tank - argh!!!

Any more thoughts would be great.

Thanks

Jon
 
you will probably think I am nuts, and ten people will disagree with me, just because... but...

the cam sensor, if so equipped, on cars with DIS, is what triggers the fuel pump relay. if the sensor is bad, it will act up in this way.

the engine of a DIS fires 2 plugs at once, so that cylinders across from each other receive spark at the same time.

so if one is sparking, so is four. if 2 then 5,if 3 then 6.
and so on. if the computer receives no signal from the cam sensor it will not activate the fuel pump relay. there might be a short int eh system. check the cam sensor for + and ground. there should be 3 wires. one will have positive juice, one will be grounded adn the other will return teh signal, measurable only with a scope. sprectrascope? not sure of what you'd call it. I don't have one.

basically, you are probably with a bad cam sensor. when a cam sensor is bad, you have a 1:6 odds that the engine will start, because if there si no signal, the pcm fires up the plugs, believed to be coming up on compression. if the correct cylinder is coming up on compression, then it will fire adn run fine, if not, it won't do anything but crank over. does this make sense? probably not, and that's why I am sure lots of peopel will contradict me, but rest assured, I worked for a Ford garage, from 87-94, before I started doing bodywork, and we had lots of problems like this when DIS first appeared in the 1989 Taurus SHO engines.

ugh...

my head hurts just thinking about it.

good luck!!!
 
Well John, that throws a whole new spin on things. I can get one from NAPA for about 25 bucks (I get a pretty good price from them). Any tips on replacing it? I figure it will be easier (and cheaper) than the fuel pump. With 145,000 miles Im sure it cant hurt either.

Thanks for the insight

Jon
 
Well here I am to disagree. John, that is a safety precaution, to prevent the pump from spraying fuel all over in the case of a leak, but I don't think that is the case here. I think that if the EEC were programmed to shut off the fuel pump relay without the cam sensor input, it would also be programmed to NOT set a code when doing so. The problem you are describing sounds more like the failure mode where the EEC will try to "guess" which cylinders to fire if it loses the sensor. That too would be an occasional no start, but shouldn't set the fuel pump code.

If I recall correctly what sets the fuel pump secondary circuit code is if a the EEC does not see the correct voltage on the circuit running from the IRCM to the pump when it commands the pump on.

The EEC applies power to the primary circuit (EEC to IRCM the EEC actually powers the relay by providing the ground) the relay in the IRCM energizes and applies power to the secondary circuit (IRCM to Pump) the EEC has a wire spliced into this circuit (pink and black wire, EEC pin 6) and expects to see 12V. If it does not see something close to battery voltage, it sets the code.

The fact that you are measuring 9.2V leads me to beleive there is a problem. Are you measureing between both wires of the inertia switch? Or from each wire to ground? (body sheetmetal)

If you measure from each wire to ground with the key on you should measure 12V on one wire (should be pink and black) and 0V on the other (should be Dark Green and Yellow). If the voltage is lower than 12 on the one wire , measure your battery voltage. You should be very close to that, if not you have a voltage drop somewhere, possibly the connector to the IRCM, or a high resistance relay inside the IRCM.

If the voltage is OK turn the key off and change your meter to measure resistance, test it by touching the meter leads together to make sure you measure 0, then measure from the green and yellow wires to body ground for resistance. This should be fairly low, I'm not sure what but if you need to know I can measure my car tomorrow for you.

The circuit may energize only for a few seconds if the engine is not running, as John indicated. If this is troubleing your measurements, you can use the fuel pump test circuit. This is the light blue and orange wires in the EEC TEST connector under the hood. This should be the only terminal in the connector with two identical wires running into it. stick a wire in there and connect it to the body ground. This is the same as the EEC providing ground to the IRCM and will switch the fuel pump relay on until you remove the wire.
 
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OH YEAH.

I am so used to mustangs I forgot that 94 t-birds were OBD-I


great suggestion about using the eec test plug for testing the fuel pump!!!


Some of the info I have offered might not jive with others, now that I reread my reply. as I stated, I knew something didn't sound quit right, and the reason being, I have had about 11 beers tonight as I surf the net, and that impairs my thinking just a bit.

now...

do whatever these guys say to do, and disregard what I say, because I am so dumb, I don't deserve to post here... I think I will go out to the garage and see if I can find the gas cap on my car. I seem to think it has ot be somewhere under the hood, but, I am not too worried, I still have 3/4 of a tank left to burn before I have to refill. That should be enough time to figure out how to put gas in it.


cheers!
 
John, that is a safety precaution, to prevent the pump from spraying fuel all over in the case of a leak, but I don't think that is the case here. I think that if the EEC were programmed to shut off the fuel pump relay without the cam sensor input, it would also be programmed to NOT set a code when doing so. The problem you are describing sounds more like the failure mode where the EEC will try to "guess" which cylinders to fire if it loses the sensor. That too would be an occasional no start, but shouldn't set the fuel pump code.



who's been drinking?
 
Well guys, Im getting damn close to joining you - I wonder how an Absolute and 7 would look w/ some green food coloring? LOL
Here's what I have. I turned the key on and found about a 2 volt drop from the battery voltage to the black/pink wire at the inertia switch. I ran a wire from the eec test (light blue/orange) to ground. The relay clicked so I rechecked the voltage between the inetria switch and the battery - nearly identical with the eec test grounded.

???????
 
Something is definitely not cool there. The voltage shouldn't drop.

Incidentally, I'm also having a 542 error on my '94 SC too, so if you happen to figure out where your problem is, it would be much appreciated if you let us know. I will do the same.

I have not done all of the voltage checking yet, because I also haven't had any no-start problems associated with it.

Dale
 
I am betting that since you are seeing the code that the EEC is seeing this voltage drop as well - meaning the problem is likely upstream from the EEC.

I would try to measure the output voltage on the pink and black wire right where it comes out of the IRCM. If the voltage is Battery or close there, your voltage drop is between the IRCM and the EEC.

If the voltage on this circuit is still 9V right outside the IRCM, it is likely the IRCM is bad, but you could check the voltage supply to the IRCM to be sure.
 
OK - Im back at it again. I checked voltage on the pink/black wire coming out of the IRCM - 9.5 volts. Checked the red wire going into it - 12 volts. I jumped the gun and picked up a different IRCM and it does the same thing so I guess I'll be posting one on the classified board once I get the vehicle working. HELP!!!! I at a loss!
 
wait wait wait...


I had this whole thing typed up adn I just erased it all because the most obvious thing was totally overlooked.


did you actually listen for the fuel pump? you can hear it running when you first turn the key on. if you can't hear it, then something is wrong back there. if you can hear it running, it's not the fuel pump. well, it could be, but, I wouldn't bet on it.

if you put your thumb on the fuel pump relay, and have someone turn the key on, you shoudl feel it click.


try some of these tests before poking around. That will give you a better idea of where you shoudl start looking. as a general rule OBD-I is not that great, as far as self diagnostics go, so, make sure you do as many other diagnostic tests as possible before going by the codes.

get back to us on what your manual checks turn up.
 
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