fuel pump dead? code 542
Thread Starter
|
Senior User
Joined: Apr 2001
Posts: 186
Likes: 0
From: Tigard+Corvallis OR
fuel pump dead? code 542
drove my bronco around this morning. Went to drive it this afternoon, and the fuel pump wont come on. I checked all fuses9in cab and under hood) and the inertia shut-off switch. Ran codes, pulled 542:"fuel pump secondary curcuit failure: PCM to ground" Any know what this could be? I also checked the voltage to and from the shutoff switch. 3 wire conector, when unpluged: 12v, 6v, and 0v. When pluged in: 12v, 6v, and 6v. Anyone know if this is right, or wants to check theirs? Tomorrow I will probably have to drop the tank and check the leads into the pump.
Posting Guru
Joined: Jun 1999
Posts: 2,415
Likes: 3
From: Comox Valley, Canada
fuel pump dead? code 542
Since you said three wires on the inertia switch I am assuming it is 92 or newer, as pre 92 only had 2 wires on them. I assume Ford added the 3rd wire to put in a light to indicate when the inertia switch had tripped. From what I understand this nuisance tripping happens.... alot 
There should be 12 volts on the dark green/yellow striped wire and 0 on the pink/blue striped wire and 0 on the grey/orange striped wire, with the plug disconnected and the key on.
When connected key on 12 on dark green/yellow, 12 on pink/blue and 0 on grey/orange.
Dark green/ yellow is 12 volts from fuel pump relay, pink/blue is wire to fuel pump motor and grey/orange is wire to "Fuel Reset" Light on dash, which means the inerita switch is tripped when the light is on.
Try disconnecting the plug on the inertia switch and jumpimg the dark green/yellow wire to the pink/blue wire. Turn key on and if all is well now the pump will run.
Could be a bad switch, or connector on the switch. Which color wires had which voltages on them when you checked?
Sparky
ps
I am reading wiring diagrams and I have never owned a EFI equipped truck. The more I read the more I am happy with carbs
There should be 12 volts on the dark green/yellow striped wire and 0 on the pink/blue striped wire and 0 on the grey/orange striped wire, with the plug disconnected and the key on.
When connected key on 12 on dark green/yellow, 12 on pink/blue and 0 on grey/orange.
Dark green/ yellow is 12 volts from fuel pump relay, pink/blue is wire to fuel pump motor and grey/orange is wire to "Fuel Reset" Light on dash, which means the inerita switch is tripped when the light is on.
Try disconnecting the plug on the inertia switch and jumpimg the dark green/yellow wire to the pink/blue wire. Turn key on and if all is well now the pump will run.
Could be a bad switch, or connector on the switch. Which color wires had which voltages on them when you checked?
Sparky
ps
I am reading wiring diagrams and I have never owned a EFI equipped truck. The more I read the more I am happy with carbs
Thread Starter
|
Senior User
Joined: Apr 2001
Posts: 186
Likes: 0
From: Tigard+Corvallis OR
fuel pump dead? code 542
[font size="1" color="#FF0000"]LAST EDITED ON 05-Sep-01 AT 02:22 PM (EST)[/font][p]here is what voltages I got for the wires. Comming from the fuel pump relay I had 6v, not 12v. Going to the fuel pump(when switch was plugged in) was 6v, not 12v. And the smaller third wire, to the light on the dash? I had 12v, even when the switch was unplugged. Does this mean the my relay is bad? Any help is greatly appreciated.
Also, am I right to assume that the fuel pump runs off of 12 volts? I tried sending a direct 12 volt signal to the pump and still nothing. But I am still confused why the voltages at the inertia switch are so weird.
Also, am I right to assume that the fuel pump runs off of 12 volts? I tried sending a direct 12 volt signal to the pump and still nothing. But I am still confused why the voltages at the inertia switch are so weird.
Posting Guru
Joined: Jun 1999
Posts: 2,415
Likes: 3
From: Comox Valley, Canada
fuel pump dead? code 542
That is neat. The way I read the diagram the pump runs on 12 volts.
There are 3 fuses that have to be checked in the Engine Compartment fuse box, "I" 20amp PCM Power Relay(supplies power to fuel pump relay close coil) ; "O" 20amp Fuel Pump Relay(supplies 12 volts to fuel pump); and "U" 20amp PCM Power Relay(supplies power to PCM Power Relay close coil).
If all fuses checkout go to the Self Test Output Connector, should be on drivers side at top rear corner of engine compartment, and ground the pin with 2 light blue/orange striped wires on it. Turn on the key and the pump should run.
If it runs It is either the Powertrain Control Module or the wire from it to the STO connector, light blue/orange striped wire from PCM pin 22 to STO connector or a problem with the PCM itself.
If it doesn't run. Well if it doesn't run check back and I will try and help some more.
Sparky
ps
Where did you jump the 12 volts to the pump at? From the inertia switch?
Thread
Thread Starter
Forum
Replies
Last Post
tigercoool
1987 - 1996 F150 & Larger F-Series Trucks
3
Aug 28, 2003 09:11 PM
93bigbronco
Small Block V8 (221, 260, 289, 5.0/302, 5.8/351W)
1
Sep 6, 2001 11:33 PM
shanaynay
Explorer, Sport Trac, Mountaineer & Aviator
3
Mar 7, 2001 10:54 PM
