: 1996 FWB - Check engine light on - Scanner turns off upon start up - HELP



6.0 Litre
08-27-11, 12:51 AM
Hello,

Could use some help here - my 1996 FWB check engine light comes on and goes off every once an while - but it is mostly on though for the past year.

Here is the issue upon plug in of the scanner to read the codes, the scanner shuts off once the start button is hit. I took it to two different shops and the scanner always shuts down and cannot read the codes to see what the issue is.

Anyone else have this problem or know what it could be?

Thanks in advance!

jayoldschool
08-27-11, 01:07 AM
The good news is that you don't need a scanner to retrieve your codes. See the FAQs for how to get the codes from the HVAC display.

turbojimmy
08-27-11, 10:52 AM
The good news is that you don't need a scanner to retrieve your codes. See the FAQs for how to get the codes from the HVAC display.

You can't get the PCM codes through the HVAC on a '96. The OBD-II codes will only come through the scanner.

I don't know what would cause the scanner to quit working. If you're lucky, it could be a blown fuse. Does your cigarette lighter work? The scan tools get power from the Data Link Connector (DLC) under the dash. Looking at the face of the connector, the pins are numbered 1-16 from left to right. The top row is 1-8, the bottom row is 9-16. Positions 4 and 5 go to ground, position 16 is 12V+ from the cigarette lighter. You should be able to put a test light or multimeter between positions 4 or 5 and 16 and get 12V. If you don't, that's why a scan tool won't work.

6.0 Litre
08-29-11, 12:38 AM
You can't get the PCM codes through the HVAC on a '96. The OBD-II codes will only come through the scanner.

I don't know what would cause the scanner to quit working. If you're lucky, it could be a blown fuse. Does your cigarette lighter work? The scan tools get power from the Data Link Connector (DLC) under the dash. Looking at the face of the connector, the pins are numbered 1-16 from left to right. The top row is 1-8, the bottom row is 9-16. Positions 4 and 5 go to ground, position 16 is 12V+ from the cigarette lighter. You should be able to put a test light or multimeter between positions 4 or 5 and 16 and get 12V. If you don't, that's why a scan tool won't work.

Thanks, yes checked all the fuses - no issues there, yes cig lighter works, the weird thing is the scanner comes on when you plug it in - it turns off when you start the scan. I'll check out the pins and see if I get 12V thanks again!

MoistCabbage
08-29-11, 12:44 AM
As jayoldschool said, you can check for codes without a scanner. Just follow the instructions here:

http://www.cadillacforums.com/forums/cadillac-seville-cadillac-eldorado-forum/138258-how-pull-codes-dtcs.html

turbojimmy
08-29-11, 09:23 AM
As jayoldschool said, you can check for codes without a scanner. Just follow the instructions here:

http://www.cadillacforums.com/forums/cadillac-seville-cadillac-eldorado-forum/138258-how-pull-codes-dtcs.html

You can't get OBD-II PCM codes through the HVAC. If the SES light is on, you need a scanner to pull the codes on a '96. On the 2000+ Northstar cars you could get OBD-II codes through the Driver Information Center, which was a really cool feature in those cars. But unfortunately, on a '96 Fleetwood you need a scan tool.

It is odd that the scan tool comes on and then shuts off. I assume from your description that you've tried multiple brands of scan tools. Other than pins 4, 5 and 16, the rest are serial data from the PCM, radio and other places. On the '96, the only information a scan tool will detect is the PCM codes (newer cars will report body codes, SIR codes, etc. and so on). You could try resetting the connector at the PCM. It's under the air box at the left front of the car. It's not too hard to get at. Unplug it and inspect the pins for damage or corrosion. This will obviously cut power to it, but I'm 99% sure that on the OBD-II cars the codes remain until they are cleared with a scan tool even after a power loss.

Cadillacboy
08-30-11, 04:15 PM
I echo on turbojimmy's reply . I could not manage to get the codes cleared thru HVAC but OBD II reader . I do use Dectron 9135 model if you're interested to know

MoistCabbage
08-30-11, 04:34 PM
This link: http://myweb.accessus.net/~090/cadidiag.html#95fltwd has specific instructions for '93-'96 Fleetwoods. it is also covered here: http://myweb.accessus.net/~090/cfb-tech.html

Are you sure it's not possible?

turbojimmy
08-30-11, 04:37 PM
This link: http://myweb.accessus.net/~090/cadidiag.html#95fltwd has specific instructions for '93-'96 Fleetwoods. it is also covered here: http://myweb.accessus.net/~090/cfb-tech.html

Are you sure it's not possible?

Yes, I'm sure. The '96 is a unique version of these cars. I kind of wish I had kept mine.

If you click through that link, you'll see that on the '96 you need a scanner to pull the codes.

EDIT: Oops - that's a different link than you provided than before. The Fleetwood might be unique, but they don't have the instrument panel that's described on that page. The Devilles had a "Driver Informaton Center" (DIC) that was below the speedo. It had the PRNDL display but also would show various trouble messages like "LOW TRACTION", "LOW FUEL" and "GET OUT YOUR CAR IS ON FIRE". Okay, I made the last one up, but it was in that area that the OBD-II codes are displayed. The description on that page is consistent with how my '01 Deville worked. Not so on the Fleetwood.

MoistCabbage
08-30-11, 04:40 PM
On the 2000+ Northstar cars you could get OBD-II codes through the Driver Information Center, which was a really cool feature in those cars.

Pulling codes through in car displays was possible well before 2000. It was possible since at least 1986 in the Seville/Eldorado. The '05 Deville was the last car that was able to display codes without a scanner, if I recall correctly.

turbojimmy
08-30-11, 04:42 PM
Pulling codes through in car displays was possible well before 2000. It was possible since at least 1986 in the Seville/Eldorado. The '05 Deville was the last car that was able to display codes without a scanner, if I recall correctly.

I'm talking about OBD-II codes. Codes that start with a prefix (P, B, S, etc. for Powertrain, Body, SIR) and a 4-digit code thereafter.

MoistCabbage
08-30-11, 05:09 PM
I'm talking about OBD-II codes. Codes that start with a prefix (P, B, S, etc. for Powertrain, Body, SIR) and a 4-digit code thereafter.

OBD II codes were retrieveable in-car, since '96. Apparently not in the Fleetwood though. The Catera also lacked this feature.

So am I to understand that it IS possible to pull codes in-car on OBD I Fleetwoods?

turbojimmy
08-30-11, 05:50 PM
OBD II codes were retrieveable in-car, since '96. Apparently not in the Fleetwood though. The Catera also lacked this feature.

So am I to understand that it IS possible to pull codes in-car on OBD I Fleetwoods?

Yes - OBD-I codes can be retrieved on the pre-'96 cars. And, to make things more confusing, you can retrieve everything EXCEPT PCM codes from the HVAC on a '96.

'96 was the first year for all OBD-II vehicles. Anything before that was OBD-I.

EDIT: and the second link for the AWH website contains bad information. It lumps the '96 into model years to which the OBD-I codes apply. As I said, the '96 uses the numeric 4-digit OBD-II codes with a "P" prefix for the PCM codes.

It took me forever to dispel the myth that the '96 had a rear-mounted, external amp too.

I don't claim to know everything, but when I see it with my own eyes....

MoistCabbage
08-30-11, 07:27 PM
'96 was the first year for all OBD-II vehicles. Anything before that was OBD-I.



Yes, I know.


Yes - OBD-I codes can be retrieved on the pre-'96 cars. And, to make things more confusing, you can retrieve everything EXCEPT PCM codes from the HVAC on a '96.


Ok, good to know.

6.0 Litre
08-31-11, 01:03 AM
Thank you all so much for the help and info. Well long story short..I took the car to a 3rd shop and I'm not sure how the the mechanic was able to read the codes, but a different shop worker told me that the o2 sensors are going bad from what the mechanic who fixed it told him. I asked how was he able to read the codes - he does not know as the mechanic who fixed it was at lunch and is now on vacation (did not even have a chance to catch him - I'll try in a couple weeks when he comes back). He also told me that there was a tear in the hose of the PCV line - how he even saw that is beyond me.

Anyways I'm happy now - but what sucks is that I'm always waiting for the check engine light to come back ON *just a year long habit of looking at it always wishing it would turn off* Well it's been 80 miles already No check engine light and I swear I've look at the location of the check engine light for the past 75 miles waiting for it to come back on...LOL

Thanks again you guys!

turbojimmy
08-31-11, 07:22 AM
Anyways I'm happy now - but what sucks is that I'm always waiting for the check engine light to come back ON *just a year long habit of looking at it always wishing it would turn off* Well it's been 80 miles already No check engine light and I swear I've look at the location of the check engine light for the past 75 miles waiting for it to come back on...LOL

Thanks again you guys!

Might have been corrosion at the data link connector that finally got knocked loose after plugging the scan tools in and out several times.

Glad you got it all sorted out. If you had a big vacuum leak (the line to the PCV is a big one), it could take out the O2 sensors over time. The car must run a lot better now.

6.0 Litre
09-01-11, 07:56 PM
Might have been corrosion at the data link connector that finally got knocked loose after plugging the scan tools in and out several times.

Glad you got it all sorted out. If you had a big vacuum leak (the line to the PCV is a big one), it could take out the O2 sensors over time. The car must run a lot better now.

Yeah me too! Yes it was a big vacuum leak as I was able to hear it - but could never find it. Come to think of it it was leaking for a while and is taking out the O2 sensors and they do need replacing now.

Oh yeah... BIG difference in acceleration too - I can actually burn off the line without the hesitation now :) no more chugging off the line upon full throttle!

Cadillacboy
09-02-11, 05:15 PM
You should also be able to get a better fuel efficiency :)