eng light due to aftermarket radio - JeepForum.com
 
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post #1 of 6 Old 09-25-2014, 03:29 PM Thread Starter
jm708
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eng light due to aftermarket radio

OK, I bought my JKU new in Feb and pulled the stock radio out and replaced it with a JVC DD head unit. I used the wiring harness and PAC and haven't had any issues. So about three days ago the check eng light comes on. The Jeep runs normal and everything works as it should. So I take it in just to make sure nothing is failing. The dealer puts it on the scanner and said it has thrown a code for not being able to communicate with the stock radio. Isnt that the reason I paid the extra money for the special wiring harness and PAC? Also I cant seem to figure why it would be fine for 7 months and now all of sudden throw a code. Any ideas or experiences???

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post #2 of 6 Old 09-25-2014, 04:51 PM
goodwrenchdave
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This just sounds wrong. Yes you will have a code from an aftermarket radio; a communication code for the radio on the interior bus; but it should not light the check engine light as that is reserved for powertrain/emissions related codes (or those modules preventing the powertrain from accomplishing it's duties may request illumination). A mickeymouse aftermarket adapter can bring the interior bus down (short) if it malfunctions.... but then you would end up with communication codes on all modules communicating on that bus.... and possibly make your cluster "sleep"/or act erraatic... The powertrain uses a separate BUS with the TIPM acting as the gateway for information from one bus to the other.

I would believe there are (or rather was) another DTC that had requesting the MIL- specifically a powertrain/emissions related code. Was the light on when you brought it in? The powertrain/emissions code may have erased itself after passing its test various times (such as evap codes). The Tech (possibly unexperienced) may not realized/reasoned of this possibility and seeing only a radio code; guessed this must have been the reason.
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post #3 of 6 Old 09-25-2014, 07:42 PM Thread Starter
jm708
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Yes the light was on for about three days including today when I took it in. I was thinking the same thing but was thrown off by the techs response. Would you suggest I just disconnect the battery to clear the code and see if it returns? Or take it to another shop (note this was a jeep dealer)? Also if the jeep no longer showed the active code why would it not clear the light as well? Please excuse my ignorance. I come from the easy era of CJ's and have not caught up to the technical nature of newer jeeps.
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post #4 of 6 Old 09-25-2014, 08:23 PM
goodwrenchdave
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There are a few things you could do (for free):

cycle the ignition key 3 times to get P-codes to display on cluster readout (if any). I believe the 2014 still does it (forgive my ignorance but I have scanners coming out of my yingyang, so I don't even bother to use this method as then I have to lookup descriptor anyways). Some work on off-acc 3X instead of off-on 3X

You could unplug the battery (minimum 15min) and possibly reset all - but then a few other inconveniences such as idle search will happen for a short duration.

or just unplug the radios PAC box (there may actually be a problem whereas it is sending out bogus data on the bus)... never seen it...but guess everything is possible. I'm running one too (PAC) with no issues on my JKU. I needed it for the uplevel amp/speakers... so it is sending out data and not messing anything up.

unfortunately to read codes other than powertrain you need a fancier aftermarket scanner or visiting the dealer service center...... maybe another dealer will scan it for free? I don't live in the states so I don't know if places like autozone have upscale scanners that will read body codes.... I hear THEY DO IT FOR FREE?
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post #5 of 6 Old 09-26-2014, 05:19 PM Thread Starter
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Thanks for the post I guess Ill see what I can get figured out on my day off on Monday.
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post #6 of 6 Old 09-27-2014, 12:35 PM
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Quote:
Originally Posted by goodwrenchdave View Post
unfortunately to read codes other than powertrain you need a fancier aftermarket scanner or visiting the dealer service center...... maybe another dealer will scan it for free? I don't live in the states so I don't know if places like autozone have upscale scanners that will read body codes.... I hear THEY DO IT FOR FREE?
Typically they scan with the same line they sell. Some stores use the top end one they stock, some use the mid range. But I am not sure even the top ends can read ALL body codes...

J Wm Bishop EA, ASADE
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