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2.3L ('83-'97) 96 ranger, 2.3, "obd communication failure" reason for failed smog


SuperE

Member
Joined
Aug 21, 2018
Messages
8
Vehicle Year
1996
Transmission
Manual
Will pass except the reason highlighted in attached image in this post. My bosch obd scan tool to clear codes and check codes works. My cigarette lighter for charging also works. Not sure where to even start except some quick generic searching ive done via google.
Recently the CEL was dead and the guy before wouldnt let me smog it and waste our time so replaced the bulb, and found out the evap purge thing near the canister was bad, replaced that with a new one, cleared code, and now its codeless. Car was driven an hour and OBD detects all emissions ready to go by the scan tool, good communication.
Anyways i have no idea what this is even about, i have not taken a multimeter to it yet since this was done yesterday (smogging). Its already a month expired on registration so need to get this moving. The guy is not a repair station, granted im a DIYer working on cars for about 20 years now and most experience with pre OBD-anything. The diagnostic port for the scan tool looks fine, the pins look fine.
I had only recently removed the valve cover and intake manifold to replace those gaskets, ignition wires, spark plugs, vacuum lines etc...and hooked everything back up a couple of weeks ago.
I have spares of EVERY sensor too, but replaced most of them when i got the car 3 years ago because it was so cheap.
Any input is appreciated.
 

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OBD2 uses standard/generic plug-in across all brands of vehicles, from 1996 and on, still used today

So if you can connect with your scanner then Smog scanner should connect, so yes that is odd

1996 OBD2 connector wiring diagram below
In 1996 Fuse 5 in cab fuse box was for OBD2 power, in later years Cigar Lighter fuse was used, so check fuse 5, 10amp

Test both Grounds(pins 4 and 5), and of course test for 12v on pin 16

Pin numbers here: https://ww2-secure.justanswer.com/uploads/Arench/2010-03-31_003842_obd.gif
 

Attachments

Last edited:
OBD2 uses standard/generic plug-in across all brands of vehicles, from 1996 and on, still used today

So if you can connect with your scanner then Smog scanner should connect, so yes that is odd

1996 OBD2 connector wiring diagram below
In 1996 Fuse 5 in cab fuse box was for OBD2 power, in later years Cigar Lighter fuse was used, so check fuse 5, 10amp

Test both Grounds(pins 4 and 5), and of course test for 12v on pin 16

Pin numbers here: https://ww2-secure.justanswer.com/uploads/Arench/2010-03-31_003842_obd.gif


Thanks, getting 12v from pin 16 to chassis ground. Pin 5 and 6 i get continuity between each pin and chassis ground. I seriously am wondering if he didnt stick the connector on all the way or something. The pins and plug are in perfect condition physically.
edit: fuse 5 was fine
 
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I would take your reader in next time
If there is still a failure to connect for the Smog unit, test it with yours at that time

The tech can't disregard their unit and PASS you, as far as I known, but it may start the ball rolling on a "glitch repair" at Smog HQ

And make sure they are using the right YEAR, later years had extra connections for modules, which won't be there on a 1996 OBD connector
 
The last time I had the Ranger through the emissions test, the first time the guy connected his machine to it, it popped up a "communications failure" message. It made him disconnect and reconnect his machine and then it was fine. I don't know what the procedure is in your state, but they should make more than one attempt.
 
Went to do my free re-test, it failed. Went to a shop where they cant smog it because it requires a shop that has dyno testing here in CA, he connected it just to see and it communicates fine.
Going to another shop that is able to test the car today or tomorrow hopefully, just want this nightmare over. Wasted 72 fun bucks, if it passes ill file a complaint with the BAR of faulty equipment.
 
Ok so update, took it to another place, the first smog check clearly shows my RPM on the readout at 15 and 25 MPH tests. My two scan tools both show real time RPM readout as well as other info.
The guy failed it (third attempt, 2nd shop first visit), said it wouldnt hold a connection and said inconsistent RPM reading. Driving half an hour around town today my scan tool never had an issue reading RPM, or disconnecting. I made an appointment with the referee to speak on Wednesday.
I might buy an OBD2 extension cable and try to resmog it, not sure at this point but my registration is 1 month expired (but paid for already).
 

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