Blinking Check engine light
 

So recently my dakota has had a blinking check engine light. When i turn the key to the "on" position the check engine light flashes, and then it makes the beeping tone while it flashes. Its the same tone as the low fuel tone but its repeating. It never used to do this, but when i turn the key to start the truck the light has been shutting itself off. I went to autozone to have them see if they could pull code a from the obd, but their scanner was giving them an error message "could not connect to vehicle".

Has anyone seen this before?

Pretty sure it is supposed to..as long as it doesn't do that with the engine running it is nothing

I should have mentioned that the flashing and noise occurs separately and after the normal bulb check. Sometimes this second event of the flashing and ringing doesnt even happen every time, which is so odd. Then even stranger is that the obd all of a sudden cannot be read anymore.

maybe its a computer related issue..I will try to remember to turn the key on in mine and watch tomorrow

Personally, I'd have someone knowledgeable take a look at it - for most makes and models, a flashing CEL means the PCM has detected/analyzed a serious problem. If a diagnostic tool couldn't connect to my PCM, along with a flashing CEL and an alarm, I'd start getting concerned. I would try to connect another diagnostic tool/reader to rule out the possibility that there was a problem with the other tool.

If other tools at other shops cannot connect either, you are probably looking at a computer issue.

Check your Fuses ... I have seen many cars where the OBD it on the same circuit as the Cig lighter .. when the readers cant connect then there is a lack of power to the OBD plug

DO NOT DRIVE IT! (while its flashing) If the Check engine light is flashing it is missing really bad and dumping raw unburnt fuel into the cats, it can cause sirious damage and or a fire. This is a universal obd2 signal. As soon as it starts flashing it is telling for you to pull over and shut off the vehicle.

Huh??

thats weird cause mine was flashing when my truck keep sdying out, but if i can get it started i will keep driving it

On all obd2 vehicles 1996+ a flashing check engine light means the the engine is miss firing so bad that raw fuel is being pushed into the exhaust system and is being blown right into your 600+ deg. f. catyletic converter which can destroy your cats and possibly cause a fire by over heating it and possibly melting it (worst case.)

I didn't read he was having any of those issues....he's been driving it.

Thanks guys! I checked my fuse box under the hood and inspected the cig lighter fuse. It was not blown and the outlet still has power to it. The second time the check engine light started flashing two days ago, the engine made brief exhaust rattle sound and i had the hood open at the time and could see the engine looked like it almost rattled too. Thankfully i did not continue to drive it after that happened.

As of today, the check engine has not flashed and there has not been any abnormal noises from the cab or the exhaust. Ill make sure to pull over if the light starts flashing while Im driving. I have a feeling that i have not seen the last of this issue, so i might break down and take it to the dealer and have them run the diagnostic scan for $116... :icon_shrug:

I was just trying to help him out. Im sorry if I have offened you.

Didn't offend me at all. Just getting clarification as I have never heard that before. Cheers. :icon_toast:

Ok good. glad to here it.:icon_toast: Ya not a lot of people know about that unless they've worked in the trade.

There are a number of things that can cause the engine to heavily misfire, but I wouldn't consider a blown fuse for the PCM - If a fuse was blown for the PCM and it had no power, you wouldn't be able to start the engine.

The definition given by carlb87 is correct (easy to find on an internet search), the cat's igniting is only a possibility due to temperatures and raw gasoline involved, but not a certainty - it probably wouldn't burn, but explode from the fumes igniting inside the cat.

Interestingly enough I had this happen when I installed the SVT injectors. The CEL light flashed and beeped and shortly after I got 'bank 1 & 2 running rich' codes (and I was). Happened every time I cleared the codes. Once the OEM injectors were reinstalled (till I can get a tune) the CEL did nothing outta the ordinary.

So my 2 cents is you have a internal fuel leak, possibly a injector sticking that is making you run rich intermittently, but maybe not rich enough to set a code, if that is possible. Try some injector cleaner in you fuel for a cheap starting point.
As for the not being able to comm with the PCM I also suggest trying another reader before you start worrying to much about that, maybe the one they tried was not CAN compatible.

i work in the trade. and i have never heard of that. also i asked my shop foreman who has been in the trade for 20+ years and hes never heard of this. care to share where you got said info from?

I first heard the explanation several years ago from dealerships of a couple of different manufacturers and then I looked it up on the internet where there was a lot more info on the topic. Dealerships can be useful :icon_biggrin:

Interesting reading. For as long as I have been working on cars, I never knew this. I don't recall seeing this information printed in any owners manual I have read. Wonder what the big secret is....

Causes of Check Engine Light Flashing
Reasons of check engine light blinking are different for each vehicle. But, a yellow or red light flashing is a serious cause of concern in itself, which is far more serious than a constant or steady check engine light. If you notice the light flashing when you drive the car in the city area, which goes off on a freeway, then you need to check for the overall performance of your vehicle in both the cases. If there is any problem in the performance and the mechanism of the car, then take the vehicle to the service center.

Engine Misfire
Check engine light flashing can be an indicator of misfire inside the car engine, which leads to catalytic converter damage, if not resolved soon. Along with the catalytic converter problem, check engine light blinking, can also be an indicator of a major problem in the emission control system of the engine. The emission control system consists of many active sensors that control the amount of pollutants, which are released by the vehicle. The flashing light can also be a denotation of dysfunctions in the oxygen sensors, which read the ratio of fuel and air inside the engine.

Spark Plug Wire
The aged spark plug wires become weak and brittle and lead to electric misfire inside the engine. Is your check engine light flashing and then getting steady, when you start the engine? If your answer is 'yes', then you need to turn off the engine immediately and check for the spark plug wires, using the OBD (on-board diagnostic) code. If the wires are worn out, then it is time to change them as soon as possible.

Loose Gas Cap
If the gas cap is not twisted correctly, then it can cause a check engine light flashing. In such cases, the check engine light blinking stops as soon as the gas cap is tightened. Sometimes, you may observe the light flashing or steady, for more than a day. In such situation, it is important to take the vehicle to the servicing center and let the experts determine the exact car problem.

It was from the ford dealership I used to work for. Everyone there had known about it.

Funny because I have had cars that actually had misfires (obd2 cars). Set a misfire code, but the check engine light never flashed on and off, just came on and stayed on. I've had shorted spark plug wires before. Never seen the light flash, only turn on and stay on until I cleared it. I wonder what the difference is to make the light flash as opposed to just setting a code for a misfire and turning the CEL on.

It's probably just an "Oh you're really eff'd now" light...haha :icon_biggrin:

Duplicate

Well what I was told is that it has to be bad enough to do damage. So it can miss reallt bad and not cause a flashing light untill a certain point. My guess would be the pcm has to see a certain number of mis in certain amount of time or a specific reading on the o2 sensors or both.

Years ago, I ran an engineering department that developed a lot of custom computerized systems for various applications & in the process in the process of development, you need to be able to test functionality & performance. To do a lot of this intermediate testing we used to develop various programs and circuits as tools to help in things like development debugging, proof of functional and performance correctness and many other things - these "tools" weren't always removed, but their functionality wasn't documented in manuals given for use by the customer, but they were documented and passed on to field service reps to help in tracing & repairing operational problems. I'm assuming that different PCM manufacturer's have different such test tools imbedded in the operational program and that this flashing indication could be one of them. As time goes on, some of these tools fall into disuse and their meaning becomes more obscure or forgotten.

'07 Dakota
 

My dad's '07Dakota just did this yesterday, while he was driving! It is idling high, around 12-1500 and is missing while driving. He has changed the spark plugs and the idle air control valve. This hasn't helped at all. Any ideas of what to try?

You need to read the OBDII codes.

He took it to O'Reilly's, and the code it gave was for the idle air control valve, which is why he replaced it, but it actually got worse after replacing it. He is calling the dealership today for an appointment, hoping he has better luck there, in the past the dealerships have been a complete joke and no help at all......he is the original owner and very precise with maintenance.

rdsmith7393
 

where can i find out how to iterpret the flashes from the check engine light on a 95 1st gen neon?

YES, while driving the truck with a flashing cel or even the lightning bolt on the dash, the pcm has detected an electronic fuel error. as stated before, serious damage or even fire will result. I have read on other charger and ram forums this case, bring it in before serious damage to your motor happens.