rotatingtriangle

Hi, so my car has a problem starting, (crank but no start) meaning I have spark but no fuel????? so I look at the fuses and relay first and found that the EGI relay has a high resistance(2 Mega ohms, it's reading O.L when I switch the range) when I measure it at pin 85 and 86 which is the control side of the relay. I further tested it by hooking up a 12v source to the control side to see if it would engage the contacts at 30 to 87. And it does... I also did a continuity test and found that I have continuity. I'm just confused if I have a high resistance in the coil why would it engage and have continuity? I also remove the cover to test the coil itself and found that I have a resistance of 80 ohms... which is normal... is it the contacts on the pin? Also does the EGI relay power the ECU? Because I'm not getting any power to the ECU. HELP

Akagis_white_comet

iTrader: (4)

This is about a Series 7, correct? As in FD3S-4xxxxx? The EGI Main Relay feeds several things, all are Black/White except Injectors (Black/Yellow) :
the ECU on Pins 4A and 4E,
Diagnosis Connector
Injectors (black/yellow)
Catalyst Amplifier
Air Pump Relay
Solenoid Valves (turbos, emissions, etc)

ECU also receives Constant Power from the Room Fuse on another terminal. Just checked in the Japanese manuals, I don't see a specification for coil resistance but your figure seems a bit high though. Most relays with 1/4" terminals (40 amps) usually have about 40 ohms resistance on their coil terminals. Micro relays (20 amp ones) are around 80 ohms. Try swapping it with the Circuit Opening Relay beside it and see if it behaves any differently? Same pinout for both, the Main Relay just has a diode on the coil pins. Try swapping your leads when measuring resistance on the coil, the diode might be skewing your measurements.

Pins 85 and 86 are the coil side, 30 and 87 are the switch side.

rotatingtriangle

Hi, thanks for the reply, and yes it's a series 7 1997 FD. I've been having this problem since last year and haven't got time to fix it over the winter. since it's warming up now I think it's time to fix this issue. Ok. I did measure it both ways to see if I would get a different reading but only got a reading of O.L. and the 2 megaOHMS reading that I mentioned. The diode you mentioned kinda makes sense for this reading. 1000 ohms to 10 Mohms forward bias and O.L when reversed. I guess that eliminates the possibility of the relay is bad. I'm still confused about which of the circuit is feeding the main power to the ECU... You mentioned the room fuse, is that one like a constant 1v feed to the ECU to retain memory? and the 4A, 4E is a 12v feed to the ECU when the key is turned to on position?

Akagis_white_comet

iTrader: (4)

Room fuse feed Pin 4B (Back up power). Constant 12v power, I would imagine for memory as you said. Pins 4A and 4E are ignition switched 12v power. For now, swap in a regular 40 amp relay in place of the EGI Main Relay and see how the car behaves. Wouldn't be the first time a relay conked out after 20 years. Got a feeling you'll benefit a LOT when I finish the Japanese FD Wiring Bible.