1995 Tacoma OBD1 vs OBD2

Owning a 1995 Tacoma, I thought I would share some info that might resolve the differing opinions regarding if these vehicles are OBD1 or OBD2 equipped.

OBD1 - There is a 22/23 pin OBD1 connector in the engine compartment attached to the front of the intake manifold near the fuse box and battery. I am unable to get the check engine light to flash using a jumper between E1 and TE1 on the OBD1 connector. This has me believing that the OBD1 connector is install but not used

OBD2 - There is a standard OBD2 connector in the passenger compartment under the dash pretty closely aligned vertically under the hand park/emergency brake. My 1996+ OBD reader works fine when using the OBD2 connector. It is hiding in plain sight, you just need to know where to look.

Why at least some 1995 Tacomas have two different OBD connectors is a mystery to me, as well as the number of 1995s that have both.

My understanding is OBD2 was developed by GM and officially became the industry standard in 1996 across nearly all vehicles. 1994 and earlier were ODB1 and there was limited to no standardization.

 

I have two 1995 Tacomas and they have both plugs.

The following is just an educated guess.

GM and Toyota were partners in the NUMMI plant where 1st gen Tacomas were made. It was however, a GM plant making Toyota and GM products.

The OBDI and OBDII plugs are in two different wire harnesses, namely the engine rm main (ERM) and the instrument panel (IP)wire harness. The IP wire harness was likely unique to Tacoma while the ERM was probably common, or very similar, with other vehicles using the same engine.

So, with GMs insight into the upcoming OBDII adoption, the plug was added to the "new" for Tacoma IP wire harness, while the OBDI was carried on with the common wire harness so no new part numbers/drawings were needed.

 

1997, I have both

 

In the early days (OBD1) each manufacturer had their own proprietary connector for diagnostics, OBD2 is a standardized connector across all makes and models and is required on all light duty vehicles 1996 and newer sold in the US although it can be found on a few vehicles as early as 1993.
Some manufacturers still included their proprietary connector in addition to the OBD2 connector, some still do.

 

Even late 1st gens have the second connector. 1995 is OBD1 but ready for OBD2 as far as tacoma goes.

 

up until 01, the DLC1 under the hood was present. 2002 and up no longer had it. the DLC1 Was standard on all toyotas. on the OBD2 cars its usually only used to access the ABS computer