QuestionQUESTION: Ok, i understand that wiring diagrams are probably needed for your advice, but I'm going to ask anyways. On a 1996 Chevy Monte Carlo Z34 with a 3.4ltr engine, the 15 amp ECM fuse on the passenger side of the engine compartment keeps blowing when the key is in the "on" position. I have no grounding issues, and I have check ignition module and crank sensors. I wanted to know, is the ECM not grounding correctly on the vehicle, or is there a ground I missed? The visible grounds are on the transmission total of 5 wires. I'm not too sure where to start or to look.
ANSWER: HI BRENT, WELL,,, LETS START OFF WITH,,, A GROUNDING PROBLEM WOULD NOT CAUSE THIS ISSUE.. THIS IS A [HOT] OR POWER LEAD TO GROUND,[SHORTING OUT] LET ME ASK YOU THIS, I WILL ASSUME THAT WHEN THIS FUSE POPS THE ENG WILL NOT START,,YES IF SO,,LETS ISCOLATE THIS. REMOVE THE MAIN HARNESS TO THE PCM,ONCE REMOVED TURN THE KEY ON AND CK TO SEE IF THE FUSE BLEW, IF NOT, CRANK THE ENGINE OVER,SEE IF THE FUSE BLEW. IF NOT THE PROBLEM MAYBE IN THE PCM OR WHEN THE PCM IS SENDING OUT POWER. SO START REMOVING SENSORS FROM THE SYSTEM,AFTER PLUGGING THE PCM BACK IN THE SYSTEM OF COURSE, CK THE IAC MOTOR, MASS AIR FLOW, ETC. CK ALL THE WIRING HARNESSES AROUND THE ENG BAY AREA, LOOK FOR ANY SHORTED WIRES TO GROUND,INCLUDING THE FUEL INJ HARNESS,I HAVE SEEN MICE EAT THESE WIRES..THERE HAS TO BE A BATTERY PLUS WIRE GROUNDING OUT TO BLOW THIS FUSE OR THE PCM IS SHORTING OUT..GET BACK TO ME WITH MORE INFO,SO WE CAN GO FURTHER IF YOU CAN. PLEASE WHEN YOU ARE FINISHED WITH YOUR QUESTIONS, WOULD YOU PLEASE RATE MY ANSWER,THANK YOU, TOM
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QUESTION: Thanks for the response Tom,
Sorry for the slow response. I have followed your instructions to remove the harness connectors, after doing that...fue DID NOT blow. I replugged the harness connectors and tried to start, I have a "no spark" condition and the 15amp fuse DID NOT blow. Kinda confused at this point...I looked at the ignition module...I have the proper 12V (DC) out of the ECM connector and the battery connector, and the .3-1.0V (AC) from the crankshaft sensor connector along with the correct .950 ohm reading from the crankshaft sensor itself. So then I tried the grounds I have the nice 12V (DC) from the module, but then when I try to start the car it drops directly to 0.0V (DC). Checked the wiring and no cuts, splices, or mice marks. Is this the symptoms of a bad ECM?
AnswerHI BRENT,DOES THIS HAVE A AFTERMARKET ALARM SYSTEM,,IF IT DOES, REMOVE IT ... IF NOT I WOULD LIKE TO SEE THIS CAR SCANNED WITH A SCANNER TO CK DATA OUTPUT FROM THE PCM..THEY WAY YOU ARE EXPLAINING THIS IT SOUNDS LIKE EIHTER A SHORT TO GROUND AS I SAID BEFORE OR IT IS POSSIBLE THE PCM IS SHORTED ITSELF.DO YOU HAVE ANY WATER PROBLEMS ?? WITH A SCAN TOOL YOU WOULD BE ABLE TO FOLLOW OUTPUT DATA FROM THE PCM,IF ANY. THIS WOULD CUT DOWN ON GUESS WORK AND REMOVING SENSORS TO ISOLATE PROBLEM..I WISH I COULD BE OF MORE SERVICE BUT THIS IS NOT ANYTHING TO DIAGNOSE BY EMAILS..IF I CAN BE OF ANY MORE HELPS GET BACK TO ME..TOM..
