Chevrolet Repair/no power to fuse marked eng1 and ecm both 20amp fuses engine compartment
QUESTION: Hi sir: this is my problem my truck 1996 chevrelet 3500 with a vortec 454 stalled on me yesterday. I noticed that the gauges went up and down really fast then the next thing was it stalled. I tried to crank it over but did not start.Today same thing cranks but nothing. So I was checking fuses and in the fuse box under the hood I noticed that the one marked eng1 and ecm both 20 amp lil fuses had no power. my battery is good fully charged and the fuse box has power. The only other thing I can tell you is that my key switch sometimes is hard to turn dont know if the key might be a lil worn out. I hope you can help me I ve herd great things about this site. THANX
ANSWER: HI FRANLIE, WELL THIS COULD BE A COUPLE THINGS THAT CAUSED THIS..FIRST BEING A BAD ECM...SECOND BAD WIRING FROM THE ECM TO THE FUSE BOX HARNESS PROBLEMS. SOMETHING GROUNDING OUT POPPING THE FUSES..WHAT I WOULD LIKE YOU TO DO JUST AS A TEST..GET YOURSELF A JUMPER WIRE POWER IT UP AT THE BATTERY PLUS SIDE AND TOUCH ONE SIDE OF THE FUSE AND SEE IF THIS POWERS UP THE OTHER FUSE AS WELL THAT IS DEAD...ALSO POWER THE OTHER FUSE AS WELL AND SEE IF THAT POWER THE OTHER FUSE UP.. I DO NOT KNOW HOW THIS TRUCK IS WIRED BECAUSE I AM NOT AT WORK AND I DO NOT HAVE A WIRING DIAGRAM TO CK..ALSO CK ALL THE WIRING HARNESS GOING TO THIS ECM MAKE SURE IT LOOKS GOOD AND NOTHING BROKEN ALONG ITS PATH..YOU COULD ALSO TAKE THE ECM OUT AND SMELL IT..THAT MAY SOUND STRANGE,BUT IF THIS BURNED UP YOU WILL SMELL IT REAL FAST. IF SO TIME FOR A NEW ECM. ALSO DEPENDING ON HOW THIS IS WIRED THIS MAY HAVE A BAD FUEL PUMP. WHEN YOU TRY TO CRANK THIS OVER OR FIRST TURN THE KEY ON DO YOU HEAR THE FUEL PUMP STARTING UP..HI PITCHED WHINE ???ONE OF THESE FUSES CONTROLS THE PUMP AS WELL... I DO NOT FEEL THE IGN SWITCH IS THE PROBLEM WITH THIS. THAT SOUNDS LIKE A IGNITION LOCK CYLINDER PROBLEM STARTING TO ACT UP..YOU WILL MORE THEN LIKELY NEED TO REPLACE THE LOCK CYLINDER IN THE FUTURE....I WISH I COULD TELL YOU FOR SURE WHAT THE PROBLEM IS BUT THIS IS ONE OF THOSE DIAGNOSTIC TIME PROBLEMS.....BUT CK THE ABOVE OUT AND GET BACK TO ME WITH MORE INFO IF YOU CAN..GOOD LUCK TO YOU,,,TOM...
---------- FOLLOW-UP ----------
QUESTION: Hi sir: Well I did run one wire to both fuses one at a time. when I touched the first one of the 2 that wernt getting any power they both powered up.I switched back n forth n they powered up only when i ran power to them. I dont know if I was supose to turn the truck on but I did n it fired rite up.Then I tried to turn it off the switch wouldnt turn the truck off so i just pulled the power wire i ran to the fuse n it turned off. the other thing is that when this happend it did not blow any of those 2 fuses. I was just testing fuses just in case when im ran across those 2 that had no power. I smelt the pcm and it does not smell burnt. Fuel pump does turn on when power at the 2 fuses.
HI FRANLIE, THE REASON I ASKED YOU TO DO THIS IS FOR JUST THAT REASON..WE KNOW THAT THE PCM IS OK AND MORE THEN LIKELY THE WIRING GOING TO IT IS OK AS WELL. NEXT STEP I WOULD LIKE YOU TO TAKE APART THE FUSE BOX,WHICH WILL BE IN 2 PIECES TOP AND BOTTOM,I WANT YOU TO CK UNDER IT WHERE ALL THE WIRES ARE FED TO IT AND LOOK FOR ANY BURNED ,BROKEN OR CORRODED WIRES THAT FEED THIS CIRCUIT. IF NONE ARE FOUND TO THIS POINT THEN I WOULD HAVE TO THINK THAT YOU HAVE FAULTY WIRING FROM THE IGNITION SWITCH OUT OR A FAULTY IGNITION SWITCH.[NOT THE LOCK CYLINDER BUT SWITCH..I KNOW YOURS IS STICKY..THE SWITCH POWERS THIS CIRCUIT UP..YOU COULD REMOVE THE SWITCH ITSELF AND CK FOR POWER COMING OUT OF THE SWITCH OR JUST PUT POWER DOWN THE WIRES THERE SHOULD BE 2 OR 3 BIG 8 GAUGE RED WIRES,, PUT POWER DOWN EACH AND CK FOR POWER AT THE FUSE THAT IS DEAD. IF IT WAKES UP THE SWITCH IS BAD... LET ME KNOW HOW THIS GOES..GOOD LUCK TO YOU ,,,TOM..