OBD I or II ? - JeepForum.com
 
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post #1 of 15 Old 04-29-2012, 05:16 PM Thread Starter
at38b
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OBD I or II ?

Evening everybody, hope you'al had a good weekend. Anyway, 94 GCL 4.0, is it obd I or II? And does anybody have an idea where the connector is? The Chrysler manual, well, it references another manual for ck'in.
Jeff


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post #2 of 15 Old 04-29-2012, 05:30 PM
DeansWings
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OBD 1, and I've heard it's under the hood? I donno, I've been drinking.

I believe 96 was the 1st obd II zj

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post #3 of 15 Old 04-29-2012, 06:18 PM
MeanGreenZJ
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OBD-1 was never tested outside of California.

Chrysler = SCI
Ford = EEC-IV
GM = ALDL, OBD-1.5 was used in a handful of cars in 94-95.
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post #4 of 15 Old 04-29-2012, 06:25 PM
Proph2010
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It is under the hood; it's just to the right of the PCM, which is in the back left portion of the engine compartment mounted to the firewall. It just a set of dangling wires with a obd1 connector plugged into a dust cover.


This is a 94 5.2 but I doubt it's different in placement.
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post #5 of 15 Old 05-01-2012, 03:10 PM Thread Starter
at38b
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Thanks for the pics, looks to be the same, now to find a connector plug for the code reader.
Thanks again.
Jeff

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post #6 of 15 Old 05-01-2012, 03:18 PM
SchizophrenicMC
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94 and earlier systems use OBD-I. 96 and later are required to have OBD-II diagnostic systems, by law.

Good luck with that diagnostic.

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post #7 of 15 Old 05-01-2012, 04:08 PM
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95 and earlier systems use Chrysler SCI. OBD-1 LOL
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post #8 of 15 Old 05-01-2012, 04:21 PM
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Quote:
Originally Posted by MeanGreenZJ View Post
95 and earlier systems use Chrysler SCI. OBD-1 LOL
I don't know manufacturer specifics, only that OBD-I was in 88 models of various make, and by law, all USDM cars were required to use OBD-II in '96 :P

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post #9 of 15 Old 05-01-2012, 04:22 PM
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Can't you do the key trick and read the blinks?

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post #10 of 15 Old 05-01-2012, 05:19 PM
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OBD-II is a standard protocol. This is why all OBD-II code readers work on all OBD-II cars. Before OBD-II there was no standard protocol and everyone used their own system. No one had OBD-I. Chrysler used SCI, Ford used EEC-IV and MECS, GM used ALDL. That is why you can not use a Chrysler SCI code reader on a Ford or a GM like you can with OBD-II.

Quote:
Originally Posted by SchizophrenicMC View Post
I don't know manufacturer specifics, only that OBD-I was in 88 models of various make, and by law, all USDM cars were required to use OBD-II in '96 :P
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post #11 of 15 Old 05-01-2012, 05:39 PM
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OBD-I application is kinda spotty through 1990 or so (the XJ and MJ was "pre-OBD" through the 1990 Model Year. However, the 1984-1986XJ with the GM V6 was OBD-I, since AMC bought those engines from GM with the control setup - the AMC engines were not OBD.)

OBD-I was specified by the CARB, and "caught on" nationally (nothing moves through government faster than a bad idea. OBD-I was poorly implemented and designed, and standards were about as standardised as plumbing.)

Sometime around 1994, SAE got involved and said "We'll take it from here." This is why OBD-II base codes (first numerical digit of zero) are standard, while the codes with the first numerical digit of one or two are vendor-specific. (The first digit - a letter - is used to define to which system the code applies.)

Also, the formats for the codes are standardised, so they may be assigned easily.

OBD-II effectively rolled out for the 1996 Model Year.

Also, OBD-II standardised the data transmission protocol and bus connector - OBD-I had different protocols and connectors for pretty much everybody - making it a good deal easier to interrogate the computer and find out what was wrong.

OBD-II also (in my experience) has a much lower error rate with self-diagnosis, I've had to repair several OBD-I equipped vehicles that threw codes that were just plain wrong.

(In any case, relying on the code without thinking about it is a mistake. A DTC will tell you the system where a problem may be found, it doesn't tell you what that problem is. It can't tell the difference between a wiring fault, a ground fault, or a failed sensor; you still have to do that. And, from what I've seen of recent auto tech training, that isn't being highlighted. That's why I tend to call them "techs" instead of "mechanics.")

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post #12 of 15 Old 05-01-2012, 06:59 PM
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Quote:
Originally Posted by MeanGreenZJ View Post
OBD-II is a standard protocol. This is why all OBD-II code readers work on all OBD-II cars. Before OBD-II there was no standard protocol and everyone used their own system. No one had OBD-I. Chrysler used SCI, Ford used EEC-IV and MECS, GM used ALDL. That is why you can not use a Chrysler SCI code reader on a Ford or a GM like you can with OBD-II.
Just throwing out what I know. My '94 GMC uses OBD-I, for example. And I've seen at least one '88 GMC with OBD-I. I could swear I read something about Mazdas and OBD-I, for that matter.

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post #13 of 15 Old 05-01-2012, 09:34 PM
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I hate to tell ya what ever it is, it isn't much. 94-95 GMC Sierra 1500 was ALDL, who's been lying to you? Read some more.

Quote:
Originally Posted by SchizophrenicMC View Post
Just throwing out what I know. My '94 GMC uses OBD-I, for example. And I've seen at least one '88 GMC with OBD-I. I could swear I read something about Mazdas and OBD-I, for that matter.
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post #14 of 15 Old 05-01-2012, 10:10 PM
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I think the deal is a lot of people consider anything older than OBD-2 to be OBD-1, when actually there wasn't a true OBD-1, it was more of a though that led to the creation of OBD-2. All the diagnostic systems for cars before OBD-2 was independant and somewhat proprietary (no standard protocols).

I really dont see the point in arguing about it, maybe people should just say "pre OBD-2" or something to that effect.
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post #15 of 15 Old 05-01-2012, 10:13 PM
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Quote:
Originally Posted by jnicewan View Post
I think the deal is a lot of people consider anything older than OBD-2 to be OBD-1, when actually there wasn't a true OBD-1, it was more of a though that led to the creation of OBD-2. All the diagnostic systems for cars before OBD-2 was independant and somewhat proprietary (no standard protocols).

I really dont see the point in arguing about it, maybe people should just say "pre OBD-2" or something to that effect.
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