Jakeboucher
Junior Member
Good evening, a buddy I rent a room to is having problems with his truck that he uses for his landscaping company. The battery was overcharged for whatever reason (Altenator problems, regulator problems, computer problems) and he was left in a no crank no start condition after battery replacement. According to him, the dealership diagnosed and said it was an alternator. So I towed the truck home, replaced the alternator with one he supplied, charged the newish battery full, and began diagnosing the no crank no start situation. Dash, lights, and display work well. Key fob will unlock and lock doors, as well as send a signal for remote start. Sending a remote start command will beep the horn and the dash display will indicate that remote start is disabled use the key to start and reset. When the key is turned to the start/run position all the proper relays energize, except the starter solenoid relay. I can jump the relay/terminals in the fuse box and the engine spins with no start. Under normal circumstances I'd suspect the ignition switch, but I have little experience with these modern wireless ignition nodes. The fuel pump circuit is being grounded out by the computer or TIPM I'm assuming. With all components hooked up properly, I have 0 volts on both sides of the 20 amp fuel pump fuse. If I remove the negative battery terminal, and keep the positive connected, then measure voltage between the 20 amp fuel pump fuse and the negative battery post, I see a healthy 12v. As soon as the negative battery terminal makes contact with the negative post, my 12v reading at the fuel pump fuse dissipates. I'm not seeing any signs of antitheft being activated, or any other sort of immobilizer. I suppose overvoltage could have burnt up one or more of the modern electrical gadgets, or "burdens" I like to call them...
I'm under the impression that the PCM regulates the battery charging on this truck, via battery temp sensor and input voltage, but I didn't see a temp sensor wire under the tray at glance. The new alternator did have a sticker on it indicating that it was not internally regulated, but infact regulated by the computer. I'll cross that bridge after I get the truck to start. I appreciate any help, I'm stumped and I don't want to suggest throwing parts at it just yet. Lol.
I'm under the impression that the PCM regulates the battery charging on this truck, via battery temp sensor and input voltage, but I didn't see a temp sensor wire under the tray at glance. The new alternator did have a sticker on it indicating that it was not internally regulated, but infact regulated by the computer. I'll cross that bridge after I get the truck to start. I appreciate any help, I'm stumped and I don't want to suggest throwing parts at it just yet. Lol.