95.5-2004 Tacomas & 96-2002 4Runners 4th gen pickups and 3rd gen 4Runners

ECU wiring help

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Old Aug 27, 2003 | 04:13 PM
  #1  
Joec500's Avatar
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From: Palo Alto CA
ECU wiring help

Hey guys....well it's me again, and I still can't pull the codes, I have used two ECU's and about 4 scanners, to no avail. So I think that there is something wrong with the wiring between the obd II port and the ECU, What I was thinking was cutting the OBDII port and spice it into the ECU a lot closer to the ECU bypassing all the Wiring behind the dash.

Any thoughts about this?? I looked at the OBDII port and it looks like there are only 3-4 wires to splice in.



Joe
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Old Aug 27, 2003 | 06:13 PM
  #2  
MTL_4runner's Avatar
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From: Montreal, QC Canada
Don't cut and splice before you check because that may not be the problem.
Just get a multimeter for like $10 and run a continuity check on the wires.
If one of the wires is "open" only then splice in another wire in its place.
Make sure to get the correct wiring diagram for your vehicle (makes a big difference!).
There should be like 6 (?) wires for the OBD connection to check.
Good luck with it.
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Old Aug 27, 2003 | 07:47 PM
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Is the check engine light on?

Why are you trying to pull codes?

When you plug the code reader in does it power up?

Gadget

www.GadgetOnline.com
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Old Aug 27, 2003 | 11:33 PM
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The engine check light has come on, I think it may be the O2 sensor. But not too sure.

When I plug in the various scanners, it says something along the lines of communication error. It just can't communicate with the ECU for some reason.


thanks for any help guys.



Joe
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Old Aug 28, 2003 | 04:02 AM
  #5  
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It sounds like it is time to break out the factory wiring schematic book and check all the wires in the diagnostic plug.

Gadget

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Old Aug 28, 2003 | 10:27 AM
  #6  
MTL_4runner's Avatar
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Originally posted by Gadget
It sounds like it is time to break out the factory wiring schematic book and check all the wires in the diagnostic plug.

Gadget

www.GadgetOnline.com
I agree 100% on that one.

You could replace the O2 sensor as a good guess, (as mine went out too) but that still doesn't help you fix any future problems or if the sensor doesn't fix it.
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Old Aug 28, 2003 | 01:43 PM
  #7  
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Well guys....the culprit was a bad MAF sensor. When I unplugged the MAF, codes pulled

And it looks like Cyclinder 5 is misfiring. But I just swapped the MAF and so far no MIL.

Still rough idle at low speeds (put in drive and idling speed)

So I think the 5th cyclinder is still mis firing. Do you guys think Fuel Injector cleanining will do any good, or should I flow test the injectors?


Joe
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Old Aug 28, 2003 | 04:07 PM
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From: North Bend, WA
I know its a PITA to pull the injectors (on a 3.0 at least). If you go to the trouble of pulling them, just get them cleaned (like at Dr. Injector in the Seattle area). The guy at the Redmond Dr Injector ran a check on the one I was working on and they were ok, he just charged a min fee to check and replaced the cones and O-rings. Also exchanged one wrong injector for a correct one.
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