Yellow Rose
Suspended
- Joined
- 22 November 2001
- Messages
- 2,256
We have heard and read many times, that to reset the ECU you pull the 7.5 amp clock fuse. I always thought this is to isolate the ECU from the battery to clear the codes by removing power. I do not have my service manual with me so I can't confirm the wiring diagram, but I am not so sure about the previous sentence. Whenever I would pull that fuse, after reinstalling it I would have to reset the clock, the radio stations and the AC settings.
Yesterday my TCS light came on by itself, without me pushing the button. I pushed the button in and out a few times but the light was still on. For the heck of it, I found a safe place to park so I could pull the clock fuse.....perhaps this was somehow related to the ECU needing to be cleared for some weird reason. I put the fuse back in, reset the AC-radio but the TCS light was still on and I had no clock display. Next time I started the car, the AC-radio settings were erased, as if the fuse had been pulled. Car started fine and ran fine, but the TCS light was still on and every time I got in to start the car, I had to reset the AC-radio. Still no clock.
When I got home I pulled the fuse to see if it was blown, but there was no sign of black smudge powder that is synonomous with a electrically blown fuse. But hey what's that? The fuse element was broken. I got out a 10x magnifying glass and you could clearly see a tiny clean mechanical break. And if I wiggled one of the male tabs, I could see how the broken fuse element would open more. The reason I had to reset the AC-radio each time started the car, was because the fuse was open. I replaced with a new fuse and everything is back to normal.
Four questions for the electrical wizards. A - If the fuse was broken, which means an open circuit then how could the AC and radio operate but not the clock? B - If the ECU is on the same circuit, how could the car start and operate ok without the brain getting power? C - If the ECU was still working with no clock fuse does that mean there is a secondary power source to the ECU? D - How can pulling the clock fuse clear the ECU if the ECU can still operate the car without the fuse?
Yesterday my TCS light came on by itself, without me pushing the button. I pushed the button in and out a few times but the light was still on. For the heck of it, I found a safe place to park so I could pull the clock fuse.....perhaps this was somehow related to the ECU needing to be cleared for some weird reason. I put the fuse back in, reset the AC-radio but the TCS light was still on and I had no clock display. Next time I started the car, the AC-radio settings were erased, as if the fuse had been pulled. Car started fine and ran fine, but the TCS light was still on and every time I got in to start the car, I had to reset the AC-radio. Still no clock.
When I got home I pulled the fuse to see if it was blown, but there was no sign of black smudge powder that is synonomous with a electrically blown fuse. But hey what's that? The fuse element was broken. I got out a 10x magnifying glass and you could clearly see a tiny clean mechanical break. And if I wiggled one of the male tabs, I could see how the broken fuse element would open more. The reason I had to reset the AC-radio each time started the car, was because the fuse was open. I replaced with a new fuse and everything is back to normal.
Four questions for the electrical wizards. A - If the fuse was broken, which means an open circuit then how could the AC and radio operate but not the clock? B - If the ECU is on the same circuit, how could the car start and operate ok without the brain getting power? C - If the ECU was still working with no clock fuse does that mean there is a secondary power source to the ECU? D - How can pulling the clock fuse clear the ECU if the ECU can still operate the car without the fuse?
