CEL Light On - No Codes Come Up

[mzcie]

Thanking all the experts here in advance. Here's hoping someone can help. 94 Explorer 2 wheel drive with 100,000 miles. After about $800 in parts and a different computer, the CEL went off 3years ago. Now the light's on again. However, when tested no codes came up on the test. The old girl runs fine and doesn't have any issues with starting or running. Does anyone have a clue why this happened and how I can clear the CEL? I'm in CA and need to get the CEL to go off in order to pass smog tests and register vehicle.

 

[MrShorty]

no codes came up on the test

Does this mean that the computer didn't seem to respond to the test trigger, or that you got all pass (111) codes?

If the computer isn't responding, I would first verify test equipment and procedures to make sure you are able to get codes.

If the computer isn't storing codes (you get 111 from CM portion), then I would probably start by checking KAM power circuit, battery cables, and such to make sure the computer has a good power supply, and good grounds.

 

[cjones101812]

you may have a short to ground on the Check Engine Light. disconnect the computer, turn key to ON position, does Check Engine light come on??

if push comes to shove, take it to a test only that does free retests. they have to pull the codes to enter it into the TAS for the inspection. if it's not an engine/emission code, it may not fail it.

 

[cybergasm]

they have to pull the codes to enter it into the TAS for the inspection. if it's not an engine/emission code, it may not fail it.

Does not matter what code if any are present in the computer. if the CEL does not function the way it's supposed too then they will fail it period!

as I found out the hard way with my 1993 Escort with this vehicle the light won't come on when you hook into the EEC test port.

don't know what the fix is yet since i have not begun to look into the problem yet.

 

[cjones101812]

Does not matter what code if any are present in the computer. if the CEL does not function the way it's supposed too then they will fail it period!

as I found out the hard way with my 1993 Escort with this vehicle the light won't come on when you hook into the EEC test port.

don't know what the fix is yet since i have not begun to look into the problem yet.

if the light does not come on with the key in the RUN position before the engine is started then it fails but, if the light is on while running:
"The TAS will prompt you to enter the code(s) from the vehicle computer. The TAS prompts the tech to Enter only those codes that could affect emission-related components (quoted from the State of CA, Licensed Smog Check Inspection Manual)

 

[cybergasm]

Thread hijack in progress......

OK, my check engine light come on when you turn on the key but not when a tester is hook up to it or if you try to do it without a tester.

And it still failed the California Smog Check!

even tho everything else is fine emissions wise.

 

[cjones101812]

they should of used a scanner to pull the codes. if they cannot pull codes/communicate with the computer then it's an automatic fail.

did they enter any codes on your report?? if not, there was most likely a communication failure with the computer.


if you would like help diagnosing you CEL let me/us know and i'll look up the diagnostics proceedures.

take care,
CJ

 

[mzcie]

you may have a short to ground on the Check Engine Light. disconnect the computer, turn key to ON position, does Check Engine light come on??

if push comes to shove, take it to a test only that does free retests. they have to pull the codes to enter it into the TAS for the inspection. if it's not an engine/emission code, it may not fail it.

Cjones - When you say disconnect the computer and turn the key to the on position, are you referring to the test scanner or the auto's computer, located on the passenger side kick panel?

 

[mzcie]

Does this mean that the computer didn't seem to respond to the test trigger, or that you got all pass (111) codes?

If the computer isn't responding, I would first verify test equipment and procedures to make sure you are able to get codes.

If the computer isn't storing codes (you get 111 from CM portion), then I would probably start by checking KAM power circuit, battery cables, and such to make sure the computer has a good power supply, and good grounds.

Thanks to everyone for replying. A friend did the test for me using a Snap-on test scanner. The battery was low during the first test and it came up with 3 codes. However, after we charged the battery, the codes were not repeated. He tried several times and never came up with any codes after the initial test. He suggested I put the old computer back in and see if the light goes off. I haven't done this yet.

Could it be that my CEL is on because of an issue non-related to smog?

Most of the replys here are beyond my expertise. I need my friend to read these replys.

 

[cjones101812]

Cjones - When you say disconnect the computer and turn the key to the on position, are you referring to the test scanner or the auto's computer, located on the passenger side kick panel?

the truck's computer

 

[cjones101812]

Thanks to everyone for replying. A friend did the test for me using a Snap-on test scanner. The battery was low during the first test and it came up with 3 codes. However, after we charged the battery, the codes were not repeated. He tried several times and never came up with any codes after the initial test. He suggested I put the old computer back in and see if the light goes off. I haven't done this yet.

Could it be that my CEL is on because of an issue non-related to smog?

Most of the replys here are beyond my expertise. I need my friend to read these replys.

do you remember what the codes were??

the majority of codes are emission related. the CEL will come on for some tranny probs also and those are normally not emission related.

did you replace the truck's computer?? (second to last sentence, first paragraph)

if he's using a mt2500 scanner it's very rare that you can't get/pull codes if they exist.

 

[mzcie]

do you remember what the codes were??

the majority of codes are emission related. the CEL will come on for some tranny probs also and those are normally not emission related.

did you replace the truck's computer?? (second to last sentence, first paragraph)

if he's using a mt2500 scanner it's very rare that you can't get/pull codes if they exist.

Thanks for the input. Is an mt2500 scanner a Snap-on? Is it used exclusively for EEC V codes? If so, then it couldn't pull the codes. We did a trouble shooting of the scanner using a CD that accompanied the scanner, but the info seemed to be for EEC V codes. Duh!

 

[cjones101812]

the mt2500 was the scanner i used when i turned wrenches and did smog checks in CA before i was injured and what i used when i did auto consulting.

depending on the cartridges(updates) and cables, the scanner will do all domestic 83 - present and imports (don't remember the years), even mercedes and bmw. it's a very good scanner and will also do data recording. make sure he has the correct cartridges in it.

make sure he connected the pigtail on your trucks connector to the scanner.

 

[MrShorty]

I've never used one of those fancy scanners to get DTC's. I've always just used a jumper wire and a voltmeter/test light. I might suggest you try the "poor man's approach" just to see if the problem is with the truck or with the scanner.

 

[BrooklynBay]

http://www.explorerforum.com/forums/showthread.php?t=202039

 

[mzcie]

Still Working on CEL

Thanks, again for all your replies to my CEL. I've finally gotten back to the CEL problem. Too much to do during the holidays baking pumpking breads and cookies.

I've checked the battery cables, taken computer out and no CEL when key's on (does that mean a short or no short?). I don't know how to check computer's ground so, tomorrow I'm going to take it to the shop and see if they can come up with any codes. I'm only paying for the test so any help with codes that come up will be appreciated. I know someone who can replace the parts for a small fee.

Thanks again guys.

 

[BrooklynBay]

Disconnecting the battery or the computer will clear the code, then it will appear again when the fault arises during driving. It's best not to disconnect anything until you find out what is causing the code.

 

[mzcie]

Disconnecting the battery or the computer will clear the code, then it will appear again when the fault arises during driving. It's best not to disconnect anything until you find out what is causing the code.

Too late. I've already pulled the computer out and disconnected the battery. I put everything back together and started her up, and about 3 seconds later the CEL came on again. So it's test time.

I printed the 3 digit self-test codes and they're all Greek to me. I'm only familiar with a couple of the terminologies used. I hope someone can explain what the codes mean after the test.

Thanks, again.

 

[mzcie]

Does this mean that the computer didn't seem to respond to the test trigger, or that you got all pass (111) codes?

If the computer isn't responding, I would first verify test equipment and procedures to make sure you are able to get codes.

If the computer isn't storing codes (you get 111 from CM portion), then I would probably start by checking KAM power circuit, battery cables, and such to make sure the computer has a good power supply, and good grounds.

I hope I don't sound too dumb, but I'm a woman with limited mechanical ability. My dad was a mechanic and I've been around cars since I was very little but have limited knowledge. Especially the newer autos with computerized everything.

Mr. Shorty, what's the KAM power circuit? I've checked the battery cables for frays and the cables have good connection. The battery's strong and the negative appears to be well grounded. How would I go about checking power supply to computer and make sure all grounds are OK? When I pulled the computer out, all wiring inside kick panel appeared to be in good condition. No bad wires and plug-in connections appeared to be OK.

Thanks once again .

 

[BrooklynBay]

KAM is the keep alive memory circuit. This is a constant power source for the computer so that it doesn't forget.