Eng 1 fuse blowing

[Dariusz Salomon]

MAF sensor is easy. Black/white is ground (middle terminal) and the pink should be 12V live with ignition on.

From memory, the trickiest part is the fight the actual harness part puts up where it enters the box.

OP: EGR is on the Eng 1 fuse circuit.

There are bolts there which you undo and it's a bit awkward.

 

[Pinger]

There are bolts there which you undo and it's a bit awkward.

Thing is, anytime I've ever dug into the fuse box, the problem has always been elsewhere.
I think those suggesting a melted wire or a fault on the O2 sensor wires are probably calling it right.

 

[97moneypit]

The fuse box can be taken apart in the sense that the back side of where the relays and fuses plug in can be accessed. From memory, one nut or bolt and then just clips to raise it out of its nest. Maybe the nut/bolt doesn't need disturbing.


I think you can add EGR to that list.

I got it apart and checked inside. I see no issues

Mine was doing that a few months ago. I found a broken wire on an O2 sensor pigtail connector, had to inspect it real close it find it. It looked like it had not been secured properly and resulted from rubbing against the chassis. I found online somewhere how to test the maf plug for correct signal to it, but don’t remember where, seems there were a few YouTube’s on that. Good luck

I have just wiggled the whole harness multiply times. I think the short is going to be 2 wires together

I think I posted how to disassemble the fuse box(at least on 97-99) -it's not obvious but doable-there are 4 slots-you need to put small screwdriver in them and pry inwards(towards fuses)-some fuses and relays gitta be removed to make room for screwdriver. Do one at the time and pull it upwards until you release all.

I got it apart

Passenger exhaust manifold. Just below the alternator. Wiring harness falls off of clip and melts on manifold

Checked all around there

 

[firestoness]

That happened on my 97 k1500 after unplugging every sensor short was still there. I opened up the fuse bow and once it was open the short was gone. One wire had a rub so I drove it home put liquid electrical tape on it and called it done. 4 months later I was driving it with the front fenders off (redneck I know) and the fuse popped again. Since the fenders were off it was easy to see where the harness had fallen on the manifold. I suspect that while opening the fuse box up I inadvertently pulled the harness off the manifold.

 

[firestoness]

Btw I think crank sensor is on that circuit too

 

[AuroraGirl]

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That happened on my 97 k1500 after unplugging every sensor short was still there. I opened up the fuse bow and once it was open the short was gone. One wire had a rub so I drove it home put liquid electrical tape on it and called it done. 4 months later I was driving it with the front fenders off (redneck I know) and the fuse popped again. Since the fenders were off it was easy to see where the harness had fallen on the manifold. I suspect that while opening the fuse box up I inadvertently pulled the harness off the manifold.

 

[AuroraGirl]

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also found this: maybe?
On models not equipped with Vehicle Control Module (VCM), ENG 1 fuse (20-amp) located in instrument panel fuse block supplies voltage to coil side of auxiliary cooling fan relay with ignition switch in ON position. A ground path for cooling fan relay is supplied by A/C high pressure switch, or auxiliary fan control switch (if equipped). On models equipped with VCM, a ground path for fan control relay is supplied by VCM. As a result, relay contacts close, allowing current to flow to cooling fan motor through relay, resulting in auxiliary cooling fan motor operation.

then a description of it:

• 21 - ENG 1 20 Amp (Yellow) IGN A Switch to Engine Loads, EGR, Canister Purge EVRV Idle Coast Solenoid, Heated O2 Sensor, Fuel Heater, Water Sensor

lastly, I see a few references that point toward repairing the ignition feed to the heated oxygen sensors , so maybe try unhooking them/checking the wiring

 

[97moneypit]

after 3 days of no luck i purchased the Haynes repair manual.

according to their wire diagrams ENG 1 fuse feeds the following
Evap can vent
Evap can purge
O2 sensors
air injection (which I believe i don't have )
Cam sensor

i did not check the Cam sensor.

when i bought this pile of **** i was told he replaced the trans at 180k miles
fast forward to me now at 210k miles
i go look at this guys crushed the harness between the trans and engine block... i am willing to bet this is the problem
i am going to just cut and repair where it goes into the trans

i am so done with this truck