AE86 electrical Problem - Drifting forum

frank · 08-05-2008, 07:59

I have had wicked trouble getting my 84 cam running, I have no fuel pump or ecu on egnition, the pump works when I wire it directly to the light.

Myself and the father spent a good while last night with a load of wiring diagrams, ecu pin outs and a multi meter.

The story is that the "Batt" pin on the ecu is gettiing constant power as is the "W" pin for the diagnostic plug. Unfortunately the "B and B1" pins which turn the ecu on at ignition stage are getting no power at all, ever.

I have checked the fueable links, fuses and relays before the ecu on this curcuit. The EFI main relay is clicking, its getting power to the back of the fuse box. It leaves the fuse box as a fairly thick black/red wire. I can find a black/red wire on the inside of the car going into an orange distrubution box before the ecu.
Unfortunately there is no current at this point and no direct link between the 2 similar coloured wires.

There is also no direct link between the B and B1 pins and anything after the EFI main relay, according to the diagram i have the current comes from the battery, throuh the fuseable link, into a 15a fuse, into the EFI main relay and onto the ECU.

My question is, is there any connector, relay or fuse in the loom from where it enters the car, to the point that it gets to the ecu.

We have checked everything else, I can now get the engine management light to come on then i ground the terminal on the ecu, so that means that once there is power to the ecu (providing the ecu still works), i should get a diagnostic code.

WHY HAVE I NO POWER TO MY ECU????

Irishtwincam · 09-05-2008, 11:17

15AMP EFI Main fuse -> MAIN EFI RELAY -> B/B1

1 - Check that the 15amp fuse gets 12v
2 - check fuse works
3 - check that MAIN EFI RELAY 12v feed comes live with the 15amp fuse in
4 - Check that when the ignition is turned on that the main relay sends this
. 12v Feed to the ecu side of the relay wiring in the fusebox.

If the 12v gets sent to the other pin, but B/B1 dont come live then its just a broken wire.
If the relay doesnt switch, its a bad relay or the ignition circuit needs testing.
Otherwise its basic continuity checking of the feed.

frank · 12-05-2008, 08:02

Sound man young master Turner

Looks like is a broken wire, im going to open the loom as much as i can this evening and start sticking pins in it, oh joy!

08-05-2008, 07:59	#1 (permalink)
frank tail slider Join Date: May 2005 Location: Cork - Ireland Posts: 76	AE86 electrical Problem I have had wicked trouble getting my 84 cam running, I have no fuel pump or ecu on egnition, the pump works when I wire it directly to the light. Myself and the father spent a good while last night with a load of wiring diagrams, ecu pin outs and a multi meter. The story is that the "Batt" pin on the ecu is gettiing constant power as is the "W" pin for the diagnostic plug. Unfortunately the "B and B1" pins which turn the ecu on at ignition stage are getting no power at all, ever. I have checked the fueable links, fuses and relays before the ecu on this curcuit. The EFI main relay is clicking, its getting power to the back of the fuse box. It leaves the fuse box as a fairly thick black/red wire. I can find a black/red wire on the inside of the car going into an orange distrubution box before the ecu. Unfortunately there is no current at this point and no direct link between the 2 similar coloured wires. There is also no direct link between the B and B1 pins and anything after the EFI main relay, according to the diagram i have the current comes from the battery, throuh the fuseable link, into a 15a fuse, into the EFI main relay and onto the ECU. My question is, is there any connector, relay or fuse in the loom from where it enters the car, to the point that it gets to the ecu. We have checked everything else, I can now get the engine management light to come on then i ground the terminal on the ecu, so that means that once there is power to the ecu (providing the ecu still works), i should get a diagnostic code. WHY HAVE I NO POWER TO MY ECU????

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09-05-2008, 11:17	#2 (permalink)
Irishtwincam Tá me sasta :D Join Date: Jun 2005 Location: Cambs Posts: 456	15AMP EFI Main fuse -> MAIN EFI RELAY -> B/B1 1 - Check that the 15amp fuse gets 12v 2 - check fuse works 3 - check that MAIN EFI RELAY 12v feed comes live with the 15amp fuse in 4 - Check that when the ignition is turned on that the main relay sends this . 12v Feed to the ecu side of the relay wiring in the fusebox. If the 12v gets sent to the other pin, but B/B1 dont come live then its just a broken wire. If the relay doesnt switch, its a bad relay or the ignition circuit needs testing. Otherwise its basic continuity checking of the feed.

12-05-2008, 08:02	#3 (permalink)
frank tail slider Join Date: May 2005 Location: Cork - Ireland Posts: 76	Sound man young master Turner Looks like is a broken wire, im going to open the loom as much as i can this evening and start sticking pins in it, oh joy!