- Thread starter
- #41
which one the is B+ terminal?
Died while driving.
- Thread starter FJ80SRT
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which one the is B+ terminal?
Yes. That looks normal BTW. You're seeing 27 year old dielectric grease in the terminals. A squirt or 2 of some WD40 or similar and a toothbrush will clean that up.
That's telling me that the EFI relay is not closed or that there is a problem with the EFI relay or associated wiring.
Pin 1 should always be ground.
Pin 2 should always be +12 from the 15 amp EFI fuse.
With the key in the ON position, pin 3 goes +12 or so from the ECU logic.
- Thread starter
- #46
Thanks. So can I rule out the fusible link as the problem, since there is low voltage the the B+ terminal? I've replaced the relay. So sounds like I may need to rewire? I hope this is not the case...
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What is the volt reading at pin 2 of the relay socket?
Is this correct?
- Thread starter
- #48
Pin 2 is 12v
- Thread starter
- #49
ECU logic?
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With the key in the ON position, does pin 3 have 12 volts ish? With the relay installed, the key cycled off to run, does the relay click each time?
A relay has a "logic" side and a "load" side.
The logic side is low current and closes the contacts for the load side which is high current.
The voltage that appears on pin 3 of the relay socket comes from the ECU and is simply a trigger to close the relay (key in ON position).
If that logic signal is not present, the relay remains open (key in OFF position).
If pin 3 of the relay socket toggles from +12 to ground with the ignition key, then the logic is good and the EFI relay is faulty.
If pin 3 doesn't, then the ECU is not activating the EFI relay for another reason and we need to go deeper.
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Have you verified all 3 fusible links off the positive battery terminal?
- Thread starter
- #53
No. It has 1.1v with the key in the ON position. The relay does not click either.
- Thread starter
- #54
Yes. All good. Do these need to be tested with the key in the ON position or does it matter?
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- #55
Using a multimeter I places the negative electrode in pin 1 and the positive electrode in pin 3. With the key in the ON position, it read 1.1v (on DC). Is this the correct way of testing this? Thanks again. I’m a newbie and love this car, willing to learn!
Did you first verify that pin 1 is ground? It should read close to 0 ohms from the negative battery terminal to pin 1 on the EFI relay socket.
If it reads correctly then, yes, you are measuring voltage correctly.
The fusible links are directly connected to the positive battery terminal. There's no need to turn anything on to check them local to the battery.
A quick check of all 3 in system:
FL AM1 (small ring terminal)-Dome lights working?
FL MAIN (large ring terminal)-Brake lights working?
FL AM2 (grey connector)-When you turn the key to ON does the CHARGE LAMP light up?
If yes to all 3, then all 3 fusible links are intact.
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Another way to do it, leave the meter to DC volts, put the negative meter lead in pin 1 of the relay socket and the positive to the + side of the battery, should read battery voltage, ish.
Not sure on the 3FE, but the later rigs, power to close the relay is from the ign switch, through the ign fuse to the ECU, then to the relay. So confirm that the ign fuse is good, with the key to run, has battery voltage ish on both sides of the fuse.
- Thread starter
- #58
Dome lights work. Brake lights light up. However, no charge lamp on the dash. Also, my multimeter won’t reach from the negative terminal to the EFI relay (pin 1). I just touched it to the bolt nearby attached to the fender wall of the truck... any other suggestions? Still waiting on that fusible link to come in the mail.
xlx
SILVER Star
My 92 3FE was blowing EFI relays and the problem ended up being the wire going into the fuse box where the relay plugs into was bad. It's underneath the fuse box under the hood. The wire gets brittle from the heat of the exhaust manifold and cracks at the connection. Need to replace the wire with a thicker gauge wire. It solved the problem for me.
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If your charge lamp (red light above voltmeter) did not illuminate WITH THE KEY IN THE ON POSITION then suspect:
fusible link AM2
ignition switch
7.5A IGN fuse (driver's left knee fuse panel)
7.5A CHARGE fuse (directly above EFI fuse in under hood fuse box)
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