mikesfastss
Club Member
99 tahoe keeps blowing the engine 1 fuse when it does it idles rough and wants to stall this fuse is under the hood.thanks motown
fuse problem
- Thread starter mikesfastss
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mikesfastss
Club Member
Yes sir it either engine 1 or engine l its a 25 amp fuse. Also its a 99 5.7 4x4 if it matters
Glancing at the schematics I should sumarily assume this is a Gas truck with a 5.7 ?
I looked them over. There are a few things on Eng 1. the heated o2 sensors are on this fuse as well as the MAF sensor. My first step in diagnoses this would be to unplug all the oxygen sensors and replace the fuse. See if it blows. If not then you have narrowed your search to 1 or more of the 02 sensors.There should be 3 or maybe 4 sensors " depending on equipment and features" 2 upstreams and 2 down streams. It would not be unheard of for a shorted oxygen sensor to blow a fuse. I think the Maf would be the least likely culprit given its total high impedance but it could happen.
There is also some Oxygen sensor wiring close to the exhuast manifold and it may be shorted or chaffed and cuasing a short. Look on the back of the engine and make sure the harness attachment clips are bolted to the cylinder heads and that the harness is not Free to flop around.
I looked them over. There are a few things on Eng 1. the heated o2 sensors are on this fuse as well as the MAF sensor. My first step in diagnoses this would be to unplug all the oxygen sensors and replace the fuse. See if it blows. If not then you have narrowed your search to 1 or more of the 02 sensors.There should be 3 or maybe 4 sensors " depending on equipment and features" 2 upstreams and 2 down streams. It would not be unheard of for a shorted oxygen sensor to blow a fuse. I think the Maf would be the least likely culprit given its total high impedance but it could happen.
There is also some Oxygen sensor wiring close to the exhuast manifold and it may be shorted or chaffed and cuasing a short. Look on the back of the engine and make sure the harness attachment clips are bolted to the cylinder heads and that the harness is not Free to flop around.
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mikesfastss
Club Member
Yes its a 5.7 gas the o2 sesnors are welded into the pipes(I bought it that way)there is a check engine light it said maf low reading and cam sensor I replaced the distributor and cleaned the maf(has a k&n filter thuoght might of had oil on it)when fuse is good truck runs perfect when it blows truck hesitates and wants to stall
mikesfastss
Club Member
So I just unpluged the o2 sensors takin it off the hoist and goin for a ride ill keep u posted
mikesfastss
Club Member
Ok so the fuse is blown after I unpluged the o2,'s so I plugged them back in and then I changed the mass air meter.fuse still blows now it blows as soon as u turn the key on.if any one can tell me where to find a wiring schematic of this truck that would be awsome
Look over the wiring to the 02 sensors. I bet its laying on something and chaffing to ground. I don't have a good way to post up schemactics but it sure sounds like that is the problem. Short to ground on the chassis or exhuast.