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No, I understand perfectly .... Posted by RS [Email] (#15) [Profile/Gallery] (more from RS) on Wed, 23 Oct 2002 13:18:35 In Reply to: I think you misunderstand..., KeithG, Wed, 23 Oct 2002 11:40:49 Members do not see ads below this line. - Help Keep This Site Online - Signup |
and what you say is in line with my understanding. What *I'm* saying involves a few things:
1. The ground point is on the engine as we all know.
2. The ECU directs hot to ground through the relay coil and energizes the relay. This is continuous as long as all the ECU conditions are satisfied for operating the fuel pump and the ECU output for energizing the fuel pump relay is good. This is consistent with what you said.
3. A relay will not necessarily close consistently if the voltage to the coil is at or below its service limit.
In this case, a bad ground has enough resistance such that, through good Ol' Ohm's law, the cumulative voltage losses through wiring, connectors, the relay coil, the ground point, and whatever else is in the circuit bring the voltage available for pulling in the relay down to the lower border of the relay's service limit. The relay's contacts do not fully engage. This isn't a problem with the ECU programming. It's just what a relay does when the voltage energizing the coil is too low to ensure full engagement of the contacts.
Anyway, I have productive engineering work to go do.
Seeya
posted by 66.21.16...
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