crazy OBD inspection problem - JeepForum.com
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post #1 of 13 Old 08-21-2019, 04:42 PM Thread Starter
jay-h
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crazy OBD inspection problem

Time for inspection again (4th since I got it). Checked out with my scanner (HF) shows everything good, 'inspection ready'. Got bounced at state inspection because 'could not communicate with OBD'. Took it to my mechanic friend, he plugged in his SnapON. All good.

Took it back to state, same problem. Brought it home, plugged in the HF scanner... again connects, everything ok.

Took it to emission repair \ reinspection shop. He could scan it fine with his shop scanner, but state scanner refused to connect. He says he has no idea why this should be. I asked if I needed a new computer, he said no, computer is fine.

Anyone have an experience like this? What did you do?


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post #2 of 13 Old 08-21-2019, 07:18 PM
Mr. Puddles
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Quote:
Originally Posted by jay-h View Post
Time for inspection again (4th since I got it). Checked out with my scanner (HF) shows everything good, 'inspection ready'. Got bounced at state inspection because 'could not communicate with OBD'. Took it to my mechanic friend, he plugged in his SnapON. All good.



Took it back to state, same problem. Brought it home, plugged in the HF scanner... again connects, everything ok.



Took it to emission repair \ reinspection shop. He could scan it fine with his shop scanner, but state scanner refused to connect. He says he has no idea why this should be. I asked if I needed a new computer, he said no, computer is fine.



Anyone have an experience like this? What did you do?
Does it connect quick or does it take it some time?

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Originally Posted by kg6mov View Post
The 4.0 is dumb old tractor motor, itís too stupid to know itís supposed to die.
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post #3 of 13 Old 08-22-2019, 03:57 AM Thread Starter
jay-h
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Well the one mechanic said it seemed a bit slow on the Snapon. The HF is always slow

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post #4 of 13 Old 08-22-2019, 07:52 AM
jtec
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this one is interesting.... keep us posted.
The insp station - cannot connect at all OR cannot turn on CEL when commanded...
Rarely is the command an issue but the thought came to me.

Some thoughts -
Will the CEL come on at every start for @3 seconds?
Check that cavity 16 of DLC has 12v.

keep us posted this has my gears turning

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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post #5 of 13 Old 08-22-2019, 08:01 AM
Mr. Puddles
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Have you tried a different inspection station?
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Originally Posted by kg6mov View Post
The 4.0 is dumb old tractor motor, itís too stupid to know itís supposed to die.
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post #6 of 13 Old 08-22-2019, 10:28 AM Thread Starter
jay-h
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To answer some questions

The error was "cannot communicate with OBD"

Tried two different lanes at inspection station as well as private reinspection shop. (mechanic at shop was surprised his shop scanner connected OK, but not the official one )

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post #7 of 13 Old 08-22-2019, 10:55 AM
wingless
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Sounds like an inspection station failure: "state scanner refused to connect".

Write them up and give them 30 days to fix the problem.


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post #8 of 13 Old 08-22-2019, 11:46 AM
LittleFootZJ
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Check the state connector for slightly bent pins. Also check your obd port for loose wires. I had a customer fail smog here in CA with their Yaris for ďcannot connect to OBDĒ. The plug had a hairline crack in it so when you tried to plug in certain tight fitting scanners (and apparently the smog station one) it would push the wires back instead of connecting because it was opening up the plug allowing the pins to push out.

I ended up getting a junkyard obd port and repinning the whole thing with the existing wires in the car and itís been fine since. My guess is someone plugged in a scanner and mashed it in the wrong way or crooked or something. Never seen another car with the same issue.


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post #9 of 13 Old 08-22-2019, 06:14 PM Thread Starter
jay-h
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Thinking back about Mr Puddles question about taking a longish time to connect.... I'm thinking maybe the ECM could be failing gradually.

There are lots of ads on the net, does anyone have experience to recommend or avoid sources?

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post #10 of 13 Old 08-24-2019, 09:05 AM
V8GCZJ
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Quote:
I'm thinking maybe the ECM could be failing gradually

If you jeep runs and everything works it's not failing. Most likely a problem with the state inspection equipment. I would contact someone in the DMV of your state and explain the problem.
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post #11 of 13 Old 08-24-2019, 05:59 PM Thread Starter
jay-h
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Quote:
Originally Posted by V8GCZJ View Post
If you jeep runs and everything works it's not failing. Most likely a problem with the state inspection equipment. I would contact someone in the DMV of your state and explain the problem.
Yes since I posted, both the emission re-test facility and a mechanic I've worked with for years said that they do not believe it's the computer. Unfortunately if there is an issue with the state equipment, it is in the design, not the individual tester. Even the retest site's state unit would not communicate but his normal shop equipment would

My mechanic is going to dig into this next week. He suspects something like a grounding issue.

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post #12 of 13 Old 08-31-2019, 05:19 AM Thread Starter
jay-h
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Update: We might be getting closer, though I will actually go for reinspection in the next few days.

I had a mechanic I've known a long time look at it, and he found one of the ground pins was open. It seems like the typical test equipment ties the grounds together but the inspection unit does not.

We'll see if that fixes things.

My toys
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'47 CJ2-A

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87 MB 560SL roadster
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post #13 of 13 Old 09-06-2019, 06:19 PM Thread Starter
jay-h
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To provide closure: Took it for inspection today and it passed. Apparently it was caused by poor ground

My toys
'89 Wrangler YJ
'47 CJ2-A

wife's toys
97 Grand Cherokee (ZJ)
87 MB 560SL roadster
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