Reply With QuoteSorry man I got nothing.... But I can bump your post!
Help with electrical gremlins
Need some help troubleshooting a couple electrical system problems I am encountering. Background: 1996 Miata with 2000 engine. My "new" engine is installed in the car after a rebuild this winter. I'm running a SDS computer for engine control, with the OEM computer operating the fuel pump, starter, rad. fans, instrument panel(?) and charging system. I have removed or "tied back" all of the oem wiring looms in the engine bay because I have removed the lights, emission control items, etc. and the oem engine sensors are not being used.
The first problem I have encountered is that the previously switched circuit that I have been using for years to power on/off the SDS system is now always hot. It is the power circuit that goes to the evap purge solenoid on the right hand side of the engine bay. This wire has worked fine as a switched power source previously- why is it now suddenly not switched anymore? Is there a relay that powers up the car's electrical system that maybe is stuck in the "ON" position?
Next problem is with the power to the fuel pump. Normally when you turn the ignition switch to "on" you can hear the fuel pump run. This isn't working now-I have not tested to see if the relay is getting power from the ign. switch, but when I connect the ground and fp terminals in the diagnostic box the fuer pump works fine.
Another problem that has popped up is when the ign is switched to "on" the fans turn on! It's as though everything that should be "off" is now "on"!
Could the lack of any sensor data to the OEM computer be causing these types of wierd problems? Maybe I just need to bite the bullet and totally abandon the OEM computer and wiring harness and build one from scratch? I plan to do that eventually, anyway, but wanted to at least get the engine started and tuned.
Any suggestion appreciated.
What's left of a '96 Miata with stock clutch.
My car exceeds my driving ability. That's the only possible explanation.
Sorry man I got nothing.... But I can bump your post!
If the switched power lead is always hot at the relay, suspect the relay.
Welcome to the world of "shared circuitry" with the fuel injection relay. You can get the fan to trigger off the SDS computer by setting an output to switch to GND at whatever temp you choose.
It sounds like your FP relay is working, are you getting signal from the FP wire that energizes the relay? Mazda is retarded when it comes to the FP relay design, I don't know what they were thinking.
Have fun using SDS 70's technology.
TXMC: Drinkin, shootin, racin!
Even though the FI relay checks out OK when tested, I have ordered a new one (as well as a FP relay). I went through the same thing a few years back with the FP relay-it tested fine on the bench, but would not work on the car! WHY IS THAT?
Hey, I'm a '60s guy working with '70s technology, so I'm ahead of the game as far as I'm concerned!
What's left of a '96 Miata with stock clutch.
My car exceeds my driving ability. That's the only possible explanation.
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