Check Engine light - Blink codes

[johnj92131]

For at least the last 6+ months, I have been getting random check engine lights that come and go.  Most of the time it is code 12 - indicating the battery has been disconnected. Last night's codes were both 12 and 22 (coolant sensor or circuit). 

 

I am pretty sure the batter has not been disconnected in quit a while (more than 100 start cycles) and the coolant sensor was replaced late last year when the water pump was replaced.

 

So the question is why would I keep getting these random codes that come and go, seemingly all by themselves?

 

Perhaps just the random Jeep electrical connector issues?  Or something more?

 

Last work on the truck was a fuel pump replacement about a month ago.  Your thoughts are appreciated.

 

Thanks,

[Dzimm]

Is there any patterns at all to your issue? More than likely you have a bad ground somewhere. I would go through and do all of cruiser's tips before doing anything else.

[HOrnbrod]

Cruiser's tips don't apply to HOs...........

 

John, I always have a code 12. Try to clear the residual memory and start from scratch:

 

Clearing error codes and removing residual memory

1. Disconnect the POSITIVE battery Terminal and touch it to ground for 30 seconds. (This is to discharge the PCM capacitors, which maintain the Adaptive Memory.
2. Reconnect the Battery Cable
3. Turn Ignition Switch to the "ON" position but DO NOT start the engine
4. Turn Headlight "ON"
5. Turn Headlights "OFF"
6. Turn Ignition Key "OFF"

The PCM Adaptive memory has now been flashed, or erased from the PCM.

[Dzimm]

Sorry, on mobile, don't see the signature. Lol

[Minuit]

Hey, considering that HOs make up somewhere from 5-10% of Comanches, it's not a bad bet to start with the Renix tips  :)

[Dzimm]

Even on HOs some of the tips can be useful and it's a good read. Really the main take away I think is to check all your grounds. No matter what vehicle you have, when you have a weird electrical issue, check the grounds.

[johnj92131]

Cruiser's tips don't apply to HOs...........

 

John, I always have a code 12. Try to clear the residual memory and start from scratch:

 

Clearing error codes and removing residual memory

 

1. Disconnect the POSITIVE battery Terminal and touch it to ground for 30 seconds. (This is to discharge the PCM capacitors, which maintain the Adaptive Memory.

2. Reconnect the Battery Cable

3. Turn Ignition Switch to the "ON" position but DO NOT start the engine

4. Turn Headlight "ON"

5. Turn Headlights "OFF"

6. Turn Ignition Key "OFF"

 

The PCM Adaptive memory has now been flashed, or erased from the PCM.

 

I will give a try to clearing the memory this weekend.  Interesting that you always have the code 12 and assume you have tried chasing it down.

 

With California smog checks, a "check engine" light is an automatic FAIL and terminates the smog test.  So this is important every 2 years.

 

Perhaps it is time to try "deoxit" on some of the PCM connections?

[HOrnbrod]

I normally have a 12 code because I most always disco the battery to work on something electrical before the 50 key strokes occur to shut it off. Surely the Cali inspectors can't be that stupid to fail you for a code 12 because you were working on something electrical and disconnected the battery, or can they?  :nuts:

 

Anyhow, the hard reset procedure above clears it. 

[Crash]

I normally have a 12 code because I most always disco the battery to work on something electrical before the 50 key strokes occur to shut it off. Surely the Cali inspectors can't be that stupid to fail you for a code 12 because you were working on something electrical and disconnected the battery, or can they? :nuts:

 

Anyhow, the hard reset procedure above clears it.

If CEL is on, failiure is immenent (sp?).

Since not OBD2, if the CEL is not illuminated longer than it's supposed to be upon starting and does not come on at all during test then it would be fine.

[johnj92131]

I normally have a 12 code because I most always disco the battery to work on something electrical before the 50 key strokes occur to shut it off. Surely the Cali inspectors can't be that stupid to fail you for a code 12 because you were working on something electrical and disconnected the battery, or can they?  :nuts:

 

Anyhow, the hard reset procedure above clears it. 

 

The problem is that people want to play games with the smog checks in an attempt to get around them.  So the ODB II port and the tail pipe sniffer are directly connected to Sacramento.  Smog stations that play games - risk jail time and their business license.  Every so often, the BAR catches somebody and the Attorney General's office is happy to make a public prosecution example.

 

Yes, just clearing the check engine light is the simple thing to do prior to the smog check