mtnkid85

Hello guys,

Im working on a 1990 manual pickup with a 1997 A/T 3.4 swapped into it. Im wanting to add in the OBDII port, which I have and I understand the 4 wires coming out of it.

What Im needing help with is locating where to connect the White shielded signal wire from the OBDII into the ECU? Which of the 4 ECU plugs is the wire located in?

I thought I was needing to look for the same white and shielded wire coming from the ecu, but I am not seeing it in there. Thats why Im wanting to know its location.

Thanks for any help,

mtnkid85

Ok so I have it narrowed down to the E5 plug, the one plug that does not come from the engine harness.
I also know it is the SDL (or I've also read some EWDs refer to it as SIL) pin.
So I went ahead and wired it up according to THIS pinout diagram on pg 52. Ran my 12+, and the two grounds.
Now plugging in my OBDII reader it won't connect, just continues to say "connecting" with out ever making the connection.
SO I assume my signal wire is incorrect?

mtnkid85

Alright so after initial testing it seems Im only getting ~6v coming from my signal wire (out of the ECU). Can any one tell me if that is correct or should it be 12v?

Both of my constant and keyed ECU 12v+ inputs are providing power.

SacRunner

Did you leave the A/T ECU and harness, or did you convert to M/T? 4Runner, Tacoma, or T100?

If 4Runner (only one I know):
A/T: it will be E11(G) pin 18
M/T: it will be E8(D) pin 19

Tacoma or T100, I don't know those EWDs.

I would recommend downloading the EWDs (Electrical Wiring Diagrams) from TIS (Toyota's Tech Information System), it'll cost you $15 for 48-hours of access but well worth it: http://techinfo.toyota.com/

mtnkid85

I bought the truck already swapped. It still has the AT ECU/Harness from a 2wd 1997 Tacoma.

Yes, I know about TIS. I am having issues accessing it on my Mac though.

According to the schematic I previously posted, I should have it wired correct. HOWEVER that schematic is for a 4wd and so my last hope is that there is a pin difference between the 4wd and my 2wd ecu.

Thanks for the reply, SAC.

SacRunner

Ok, I apologize, I read your first post and gleamed over the other two.

Yes, you will need the two ground wires connected correctly at the OBD-II port; I initially only had one, my two scanners worked just fine, but the scanner that the SMOG ref had didn't read until I connected that second ground.

The SDL wire is a digital signal wire, with a square wave of data passing through it alternating between a digital '0' and '1' (it's likely alternating between 0V and +5V). The best way to see if it's outputting data correctly would be to attach an oscilloscope (which most people don't have) to watch the square wave pass by on the screen. The other option would be to set your multi-meter to A/C and see what it shows (I don't actually know what to expect).

In general, I would double/triple check that the pins in the OBD-II connector are correct (which it sounds like you have). For mine, it was 4 wires: SDL (W at pin 2), Connector GND (W-B at pin 4), Signal Ground (BR-R at pin 5), then +12V (always on, with a 7.5A fuse, V at pin 16).

mtnkid85

I am 99% sure Ive got the OBDII connector pinned correct. I probed my other vehicles OBDII connector and the SDL wire also gives off ~6v in those too.
So, I called in a favor and am having a friend print out all of the correct EWDs for me. So ill be able to update if there is a difference between 2&4wd ecus.

Next up, is I suspect the edu is not turning on the check engine light either. When you go to start the truck the CEL illuminates with all the other lights in the cluster.
But I think the motor has to be throwing codes, even though the CEL isn't on in the dash.

mtnkid85

Alright, well I now have a hardcopy of the Toyota TACOMA Electrical wiring diagram. A quick glance through it shows, I do have it wired correctly. No difference between 2wd and 4wd.

SDL in is pin 18 in the E5 plug.


SOOOO, F. Don't know where else to go. I guess Ill be going through it all when I have time to double check everything else the PO did.

Does anyone know where to look for the wire that sends a signal to illuminate the CEL in the dash? It has to be located in the E5 plug too doesn't it (its the only plug that isn't part of the engine harness)?

mtnkid85

Another question, in the EWD the SDL line says "shielded" what does that mean? Is the entire SDL wire supposed to be encased in a grounded wire?
As I have it right now, its just a straight single wire connection.

SacRunner

The "shielded" part just means that, yes, there's a ground wire (usually a "mesh" of sorts) wrapped around the signal wire. Typically, the wire is constructed with the standard stranded copper wire at the center, then some form of insulation, then the metal shielding layer, followed by an outer layer of insulation. Then the shield wire it connected to ground.

The shield does nothing if it is not grounded, the goal is to prevent any odd electrical "noise" from impacting the digital signal on the wire, and by wrapping the signal wire in a ground shield any "noise" is sent to ground and leaves the signal wire alone.

mtnkid85

Well after walking away from it, I came back looked at the D7 plug and right off noticed I had the SDL line in the #7slot not the #2 slot. Moved it and BAM connected!

So yea, this truck has... EIGHT codes stored!

Lordaragon181920

Which are the 2 wires , who come out from the ECM and connect in OBD2 AND WHICH points they connect on OBD2

Shawn M

Hi, I’m working on a 95 runner I just purchased with a 98 3.4 swapped. I’m trying to wire in the E5 plug to access the OB2 reader on it.

I have everything wired for the plug for the OB2 but what other wires on the plug need to be hooked up?

Thanks