: Diagnostic Mode in '94-'96 Fleetwoods....

04-29-06, 10:41 AM
I found out yesterday that the 94-96 Roadmasters have a diagnostic mode accessed through the climate control like my deVille, I was wondering if the Fleetwoods had it too. Here's how you access it:

Press Auto and Up Temp together for a few seconds until the screen lights up and a "--" appears. Then press High Fan to scroll up through the numbers.

I was told that the FWB's don't have it, and that it's a Roadmaster only thing, which I think is odd that GM would only put something like this in a Buick, when all the other Caddies have it. I'd try it out myself, but there aren't any LT1 FWB's for sale in my area.


04-29-06, 10:56 AM
They all have it.

04-29-06, 10:59 AM
You can enter the diagnostic mode by simultaneously pressing the "OFF" and "WARMER" buttons while the ignition is in the "RUN" position.
Read more here:

04-29-06, 11:12 AM
This makes the Fleetwood Brougham far better than the Town Car now!

Do the 90-92 models have it?

04-29-06, 11:38 AM
My dad's 93 Park Avenue has it too. I guess any car with electronic climate control can pull its own codes.

04-29-06, 11:46 AM
All GM cars or all cars in general? Wonder if Ford's used this too.....

04-29-06, 12:07 PM
The earlier models have the "Data Link Connector", you can locate it under the dash, in the center, under the ashtray, if I remember right.
This is a 12-pin connector, to enter the diagnostic mode you turn the ignition "OFF", then connect the two upper right terminals with a piece of wire. Turn the ignition to the "RUN" position and watch the "CHECK ENGINE" ligt. This light will flash the trouble codes, if any.

Read more here:

I dont know, if there are the Brougham RWD codes now, sometimes, they disappears, but I have it stored in my computer, in case of necessity I can send you the codes.

04-29-06, 12:37 PM
Yeah I remember using the DLC and a scan tool on my Roadmaster for a lab in my vehicle services class in my senior year at high school. Thats the old style way, on board diagnostics like caddy has used since '82 is the new way!

04-29-06, 12:43 PM
1990-1992 Broughams do have it. Like I said they all do. But not all GMs do that. I think you only have to jumper that plug under the dash on the Broughams with Carberators or at least I think that's what some people said before. There are a bunch of posts about it. On the older ones you can use the buttons too. There's probably a way to get the codes from the Lincoln too but it doesn't make anything much better if they don't. You only need to get the codes if the service light comes on.

04-29-06, 12:56 PM
Yes, the FWD have it, but the RWDs (Im not sure if the 90 - 92 too) have not the gimmick with "OFF" and "WARMER", you only can use the jumper on diagnostic connector - thats the experience with my 3 Broughams RWD I had (85 + 2 x 88).

04-29-06, 03:48 PM
You can do the off & warmer thing with older ones. There are people here who have early 80s ones who did it before.

04-29-06, 05:30 PM
They started that in '82 right?

05-05-06, 05:37 PM
I checked for a diagnostic mode in that '84 SDV I drove today, yup it's got it :) Accessed thru off and warmer IIRC.

Night Wolf
05-05-06, 05:53 PM
Yeah, I was able to pull codes from an '83 Eldorado using that too.

I just don't see how the on board diagnostics makes a car better then another... I mean, yeah, its great for troubleshooting... but really it isn't like you can't buy a scan tool... I woudln't that limit me on buying a car.

Atleast the Caddys have it tho, and thats what I plan to stick with :).

05-05-06, 06:13 PM
Scan tool you could do too, but when I wanna see the RPM's when I'm driving, I dont wanna have to deal with all those cords and stuff.