ignition fuse wiring

i have a 95 ford econoline that blew the 60 amp ignition fuse in the power box and just as quick blew the replacement.the fuse is fine with the key in the off position but will blow in about 30 seconds in the run position. what i require is the wiring diagram for this 60 amp circuit in order to start to trace my problem    sam

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loretto

no,nothing has ever been done to the van.and had just recently completed a 7000km. trip whenever the fuse blows the powerwindows stop also i disconnected the harness from the steering column[key switch] and found my power coming in fine but there did appear to be a short on a gray / YELLOW wire that is why i need to know exactly what the 60 amp ignition circuit feeds   sam

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loretto

POST EDIT: Rethinking, I doubt this is the problem since you are talking IGN powered. It probably is some power window short...
/end PE


Disconnect the alternator's main power (the heavy to the battery +12V) in case its power diodes have shorted, but that circuit shouldn't be ignition switched (it is permanently connected).

To avoid fuse (flink) blowing, you could use a lamp instead - in this case a headlamp (55W, 100W etc) which will light fully if the short is still present.


An BTW - disconnect the battery's negative terminal BEFORE the alternator's power wire.
(REMember - whenever playing with "hot" wires, the battery's chassis (negative) connection MUST be disconnected.)

hi,
to clarify we are talking of the 60A fuse labeled ignition switch as there are four other 60A fuses in the underhood panel.
the 60 amp ignition fuse protects all the wiring at the ignition switch.
grey / YELLOW output of the switch feeds circuits such as heater, abs, air bag, transmission controls, drl. however, these all have individual fuses, which aren't blowing i presume. these are all fused in the underdash fuse panel. the heated oxygen sensors, also on this circuit, are only fused by the main fuse. the grey / YELLOW heads to the fusebox and to the o2 sensors.
m

yes, we are talking about the 60 amp fuse in the power distribution box labled as ignition..as a side note the if a new fuse is put in the engine will fire up and run for about 30 seconds until the fuse blows. i am also assuming that it must be a solid short/grd on a fairly heavy wire as if not i would think a lighter guage wire would burn off before the 60 would blow. pls. keep the info coming as it gives me more options to check when i get back to it   sam

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loretto

is it possible that this circuit enters the switch[key] comes out goes to the fuse panel and is also routed back to the distribution box to feed a maxi fuse or relay. i am going to our library in the next few days to see if they may have some info but i am not hopeful but somewhere i have to get a rundown of 100% of where it goes. when not running there is good power going to the heavy alt. wire. but the guage shows discharge when running which i assume is as a result of the short/grd.

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loretto

With the key in the on position but the motor not running, does it still blow after 30 seconds?  If not, you may want to inspect the wires going to the O2 sensors.  See if the one in the front of the vehicle is possibly laying on the exhaust manifold and the heat from the manifold is melting the insulation away from the wire allowing the conductor to make contact with the manifold.

yes, with the key in the on position the fuse will blow in about 30 seconds. sam

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loretto

i am an idiot wrote:

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With the key in the on position but the motor not running, does it still blow after 30 seconds?  If not, you may want to inspect the wires going to the oxygen sensors.  See if the one in the front of the vehicle is possibly laying on the exhaust manifold and the heat from the manifold is melting the insulation away from the wire allowing the conductor to make contact with the manifold.

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Yes it will. So is there any developments yet? Anyway, have you had a DIY manuals in your library? Best refer to the car manual to make sure every wiring system is not affected.

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NanoCar
VintageGuy

Why do you ask or care, or are you simply a spamster?
Two more names for the blacklist?
And a few addresses to add to the html spamlist corruptor...

O2 Heaters should have a separate fuse for their power supply.

Most likely they are fed from the 60amp IGN feed and then branched off separately to their own respective fuses.

FINALLY GOT A DIAGRAM AND TRACKED IT DOWN. THE O2 SENSORS IN 95 WERE PROTECTED ONLY BY THE 60 AMP FUSE . IN PRETTY WELL EVERY OTHER YEAR THEY WERE PROTECTED ALSO BY A FUSE IN THE PANEL SO ONCE I KNEW THIS IT ALL MADE SENSE   PINCED WIRE NEAR THE MANIFOLD. THANKS FOR YOUR HELP   SAM

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loretto