: 81 v8-6-4 fuel economy indicator????



Adrian12
07-05-10, 03:46 AM
hi cadillac-friends

i've a question. in my service manual is written that 81 cars have a green and amber indicator light for good or poor fuel economy in the dashboard...

i saw that i dont have lamps in it, put some in and next i saw, that i don't have wires for these lamps in the connector of the dashboard instrument lights.

now i would like to know if this feature all cads had or was it an option for higher price??

i'd like to have this nice feature.

where is the vacuum switch for this mounted? has anyone a picture, because i think i have a switch, but it looks like different than in the book. near the main-connecor on the firewall i've a vacuum switch with 2 wires but 2 vacuum lines too (in the book is written that it has 1 vacuum line)

thanks a lot for your help :)

adrian

jayoldschool
07-05-10, 01:09 PM
Which engine do you have?

Adrian12
07-05-10, 02:35 PM
Which engine do you have?

6.0 v8-6-4 (like in the title)

or do you need some other information?

i've the wholes for the 2 bulps in the dashboard but the connector of the dashboard doesn't have the 2 wires for the 2 bulps...

and so i'm not sure if i have the switch too.. but i would like to have ;)

thanks

jayoldschool
07-05-10, 02:49 PM
lol, didn't even think of the title!

Well, the 81 got the fuel economy/cylinder display so it is not surprising that there is no provision for the lights. No need for a green or yellow light when one can see the actual real time or averaged mileage. Perhaps the lights were for the V6 and the diesel? I'll look it up in my FSM some time. It probably mentions the feature in the 1981 brochure, as well. You can find it online easily with a little google work...

Adrian12
07-05-10, 03:24 PM
lol, didn't even think of the title!

Well, the 81 got the fuel economy/cylinder display so it is not surprising that there is no provision for the lights. No need for a green or yellow light when one can see the actual real time or averaged mileage. Perhaps the lights were for the V6 and the diesel? I'll look it up in my FSM some time. It probably mentions the feature in the 1981 brochure, as well. You can find it online easily with a little google work...

in my manual its described, but ther is no explaination for what engine it is. so i thaugt it would be a nice thing to have it on my engine :D

its only the switch out of a vacuum line, so that shouldnt be the problem, but a pic of the switch would be helpful :)

thx for your help

Bro-Ham
07-07-10, 03:29 PM
Adrian, The feature you are talking about is called "Fuel Monitor System" and, as far as I can tell, the last year it was available was on the 1980 Cadillac deVille and Fleetwood Brougham with the 6.0/368 4bbl V8. I can't see the option as being available in 1981 in any of the sales literature, likely because the V8-6-4 had an instantaneous fuel economy indicator in the fuel data panel. Here is the lingo about this option from the 1980 Cadillac brochure: "Fuel Monitor System. Color-coded lights on the instrument panel indicate relative fuel use. Not available for diesel." Hope this helps. :) Dave

jayoldschool
07-07-10, 05:11 PM
I knew someone would know what I was talking about. Thanks Dave!

sven914
07-07-10, 08:20 PM
I would like to see these lights... Anyone got a picture of them working? It sound like something they should have re-installed on the 307 equipped Cadillacs, after they deleted the Trip Computer.

Bro-Ham
07-07-10, 09:52 PM
I would like to see these lights... Anyone got a picture of them working? It sound like something they should have re-installed on the 307 equipped Cadillacs, after they deleted the Trip Computer.

Sven, Fuel economy wasn't on the minds of as many car buyers in 1989 as it was in 1979 during the gas crisis.

My favorite uncle had a fuel economy gauge in his new 75 Electra 225 Sedan (red, white top, red vinyl interior - boy did I LOVE that car!), I was an 8 or 9 year old kid at the time and we were driving along, and I asked him what the fuel economy gauge was; he looked at me, amused, and said it was "for the ladies." :) I assumed that meant, to him, that since women presumably didn't know how to drive that they would need a special gauge to let them know if they were doing it properly. :) He was a total classic!

Since I know you're already making preparations in your mind to install this feature in your car, here is the info from my 79 owner's manual so you can get an idea of what it will look like once you get it retrofitted into your warning light display module in your car. :)

sven914
07-07-10, 10:42 PM
Since I know you're already making preparations in your mind to install this feature in your car, here is the info from my 79 owner's manual so you can get an idea of what it will look like once you get it retrofitted into your warning light display module in your car.

Cool, thanks for the idea.

Last time I was looking at my tell-tale with a flashlight, I noticed a blank square with two dots in it. Now I know what that was for (looked just like the picture).

http://www.cadillacforums.com/forums/attachments/rwd-19xx-1984-deville-fleetwood-1985/59961d1278549883-81-v8-6-4-fuel-economy-img_4983.jpg

For some reason, I thought they had actual idiot lights, that either said Good or Poor economy.

But hey, since I already have the slot in the dash, I might as well think about installing the system (not that I care about fuel economy). Too bad none of the junkyards here don't have any '70's or '80's Cadillacs to cannibalize. If it's just a vacuum sensor and some LED's, it should be simple.

drmenard
07-07-10, 10:44 PM
On the 1981 caddy with the 4-6-8 set-up had this gauge on the lower right of the center of the dash...Hope these pictures help..

jayoldschool
07-08-10, 12:15 AM
Actually, that is the gauge from the 82-85. No "Active Cyl" button ;)

Bro-Ham
07-08-10, 12:31 AM
Sven, the fuel monitor system was standard on the Seville from 76-79. Talk to Craig, 77CDV, he says the salvage yards near him are loaded with the type of cars you're looking for - maybe he could help. We all want to see your car full of the gadgets and trim that make you happy. :)

Adrian12
07-08-10, 03:46 AM
Cool, thanks for the idea.

Last time I was looking at my tell-tale with a flashlight, I noticed a blank square with two dots in it. Now I know what that was for (looked just like the picture).

http://www.cadillacforums.com/forums/attachments/rwd-19xx-1984-deville-fleetwood-1985/59961d1278549883-81-v8-6-4-fuel-economy-img_4983.jpg

For some reason, I thought they had actual idiot lights, that either said Good or Poor economy.

But hey, since I already have the slot in the dash, I might as well think about installing the system (not that I care about fuel economy). Too bad none of the junkyards here don't have any '70's or '80's Cadillacs to cannibalize. If it's just a vacuum sensor and some LED's, it should be simple.


yesterday i put cables into the dashboard with the 2 bulps. bulps are working when i put cable to ground :) i ordered on ebay a vacuum switch that controls the 2 bulps.... the switch will be in austria in 1-2 weeks then i'll let you all know.

i think its a nice option, this additional indicators, because not everytime you have a look onto the montior next to AC-control panel.

thanks for now - i'll let you all know if it works :)

adrian

sven914
07-08-10, 02:01 PM
What's the manufacture and part number of that vacuum switch?

Bro-Ham
07-08-10, 05:48 PM
that does it - I'm installing this fuel monitor system in my car too... :)

drmenard
07-08-10, 07:07 PM
Okay Jay ....you got me... that was the first one I found.. Here is the right one...

creeker
07-08-10, 07:28 PM
My 1980 cdv had that light, (368) it was in the dash board right below the
dashpad, very small light, cant remember if it was green or red, I think it was more of a novelty than anything, it took very little gas to actuate
it, if you were to back off on the gas pedal evey time it came on,you would never get to where you were going.

Bro-Ham
07-08-10, 08:26 PM
drmenard, that is the 1981 mpg sentinel, later named "fuel data" once no one cared about mpg in the mid 80's. :)

sven914
07-08-10, 08:31 PM
^They make great coolant gauges.

Bro-Ham
07-08-10, 08:44 PM
Sven, I saw your temp gauge, very interesting. I could not do that because I have the rear defogger switch in that area. I thought about a 77-78 rear defog and power antenna together switch for my car so I could control the antenna but decided it was too much work. :)

sven914
07-08-10, 09:45 PM
Dave, your '79 had the option to have these fuel economy indicator lights, right? Or was it standard?

I just found a '77 de Ville in a local junk yard and two '78's up in Cleveland. Could you check in your sales brochures to see if the '77 or '78 has this system?

Bro-Ham
07-08-10, 09:51 PM
OK Sven, I can't locate my 75 brochure but have the newer ones: fuel monitor system was an option in full size deVille Fleetwood in 1976, 1977, 1978, 1979, 1980. Standard on all years of the first generation Seville. My 79 does not have the option - wish it did because it also had a low fuel indicator. Of all the 77-79 Cads I've owned, had in the family, or seen, I've not seen this option on any of them. I'm sure they exist.

sven914
07-08-10, 10:03 PM
OK Sven, I can't locate my 75 brochure but have the newer ones: fuel monitor system was an option in full size deVille Fleetwood in 1976, 1977, 1978, 1979, 1980. Standard on all years of the first generation Seville. My 79 does not have the option - wish it did because it also had a low fuel indicator. Of all the 77-79 Cads I've owned, had in the family, or seen, I've not seen this option on any of them. I'm sure they exist.

Thanks. There is another yard (between the local one and Cleveland) that has a '77 Seville, so if the de Ville doesn't have the system, I got options.

Bro-Ham
07-08-10, 11:30 PM
good luck Sven, I'm sure you'll find what you're looking for since I know how determined you are once you get something in your mind. I can't wait to see the pictures you post with the funny little lights blinking away giving you hours of driving entertainment. Gotta love these cars. :)

sven914
07-20-10, 05:57 PM
Well I installed this fuel monitoring system...

http://carphotos.cardomain.com/ride_images/3/4000/4267/34999633107_medium.jpg

http://carphotos.cardomain.com/ride_images/3/4000/4267/34999633093_medium.jpg

http://carphotos.cardomain.com/ride_images/3/4000/4267/34999633121_medium.jpg


After fighting off a nest of hornets, with Fix-A-Flat and a rubber hose, to get the switch out a trashed '77 Seville, I spent hours dealing with a bulb that would not light because of high resistance in the low vacuum indicator circuit, and after finally getting everything working properly, I have realized that the 307 does not experience enough vacuum loss on acceleration, to get the indicator lights to switch from economical to gas guzzler (0-75, WOT, uphill, should have done something).

I have disconnected the system, because I do not need a light to tell me the engine is running (that's what the exhaust leak is for). I will probably recycle this effort at a latter time and try to use the switch as an EGR indicator or something along those lines.

sven914
07-21-10, 06:21 PM
I just realized, it might not be the engine, it might be the switch. Even the 307 should only pull 1-1.5 inches at WOT and that should be enough to trip the switch. In fact it should switch with vacuum below 7-10 inches. I know at 0 vacuum, it switches to the low vacuum indicator, so I guess I need a vacuum pump to see how sensitive this thing is.

Adrian12
07-22-10, 03:02 PM
hi friends

i got the switch of a end 70s cadillac work in my 81 v864 fuel injected cadillac :)

it works very very fine and is a nice "game".

the only fact is, while driving and go away from throttle (pedal not depressed) amber light works but i'Ve no other option on vacuum hoses to get it work, but it doesnt matter, it works fine on depressing throttle from green to amber and back hihihihihi

sven914
07-22-10, 09:10 PM
^Yeah I think the one I got is messed up from sitting too long. I have to test it with a vacuum pump, to see exactly when it switches, and if there is anything I can do re-calibrate it or something. Other wise, at least I have the switch, I know what it looks like (so I can get another one), and I know how to wire it to make it work.

1980coupe
07-26-10, 04:10 AM
My 1980coupe has that feature. Pretty cool. I have always been asked whats it for. Tell them its the Fuel Econmy Switch. On high acceleration and intial start up it goes to amber and on low goes to green. Wasn't working for a while but got it fixed. Thought I had my service manual with me but I don't.

sven914
10-18-10, 06:17 PM
I got another switch today, so I should be able get this monitoring system working. One problem I ran into was that the '80 de Ville I was cannibalizing didn't have the bulbs or the sockets for the indicator lamps. Does anyone know what size lamp socket was used for the indicators in '80 (was it the 5/8 inch)? And what is the bulb number for those sockets? I know the 194 was the standard bulb for the other lamps, but rockauto also gives the option for a 906 and a 74 bulb.

I also need to know what pins on the telltale work the indicators, so I can wire the system correctly through the factory connector. Can anyone with an '80 post a picture of the wires behind their telltale?

1980coupe
10-18-10, 06:58 PM
I got another switch today, so I should be able get this monitoring system working. One problem I ran into was that the '80 de Ville I was cannibalizing didn't have the bulbs or the sockets for the indicator lamps. Does anyone know what size lamp socket was used for the indicators in '80 (was it the 5/8 inch)? And what is the bulb number for those sockets? I know the 194 was the standard bulb for the other lamps, but rockauto also gives the option for a 906 and a 74 bulb.

I also need to know what pins on the telltale work the indicators, so I can wire the system correctly through the factory connector. Can anyone with an '80 post a picture of the wires behind their telltale?

it's a 74 bulb and I took a pic but I'll load it up at the computer at work. Here at my home it takes FOREVER! I can tell you that the pins or where the bulbs go in is in between the washer and security system tell tale lights. All you do is put in and twist to lock in. If you still need the pic, I'll upload it but later. ☺

sven914
10-18-10, 08:17 PM
The picture will help if it's not too much trouble. So it goes between the black/white wire and the dark green wire, right?

1980coupe
10-18-10, 10:16 PM
The picture will help if it's not too much trouble. So it goes between the black/white wire and the dark green wire, right?

dont know what wires you are reffering to, but I was wrong on one of the tell tale lights, goes in between the washer and the trunk tell tale lights. I've found that some cars that are not equipped with this feature still share the same instrument dash strip so you should see two little round circles on the face of it. I'll upload shortly...

1980coupe
10-18-10, 10:38 PM
here's a pic hope it helps you out....
http://i55.tinypic.com/2dl7ofl.jpg
also on my service manual it reads that on the 18-way connector found under dash the min. fuel economy is number 11 and wiring color code is 20 yellow; the one for the max. fuel econmy is number 12 and wiring color code is 20 white.
The way it reads is look at connector as sitting in car, far right bottom row is number 1 and it goes from right to left and ends at number 9 second row above number 9 is number 10 and reads left to right and ends at number 18; hope it helps ☺

sven914
10-18-10, 10:54 PM
Thank you... I knew which holes the bulbs went in, but from your description of the connector, I should have no problem finding the right pins.

1980coupe
10-18-10, 11:17 PM
Thank you... I knew which holes the bulbs went in, but from your description of the connector, I should have no problem finding the right pins.

your welcome, glad I can help☺. I was going to scan the page but my buddies here at work are gone and have no access to their scanner. If you need anything let me know, I got my service manual with me!

sven914
10-30-10, 08:55 PM
Finally had a bit of success (not complete, but acceptable).

http://carphotos.cardomain.com/ride_images/3/2503/2889/31256444012_large.jpg

The switch I found in the Seville was defective and wouldn't actually switch between high and low vacuum. I found this white one bolted to the firewall of an '80 Coupe de Ville. After some probing with a test light, I found that the knock solenoid was the best place to bolt the switch. The vacuum source is the manifold line that runs to the charcoal canister.

http://carphotos.cardomain.com/ride_images/3/2503/2889/31256444010_large.jpg
http://carphotos.cardomain.com/ride_images/3/2503/2889/31256444011_large.jpg

As pointed out by 1980coupe, the bulbs for the monitor go into the two small hole in the telltale. On the 18 pin connector, the pins for the monitor are empty and there is nothing contacting the printed circuit. For the wires to make the connection, I found a spare 18 pin connector and preyed out the pins, and spliced them to the wires I used for the circuit. They snap right in to those holes and make a solid connection.

Here is a video of the monitor in action. I apologize for the blurriness; my camera was really cheap...


http://www.youtube.com/watch?v=TfFmXxANGsg

You might notice that only the green indicator is on. The amber one comes on at bulb check, but after a minute fades out, so there is some resistance in the low vacuum indicator circuit, which I'll deal with later. For right now I'm just happy that to have a green light to tell me I'm being good...

1980coupe
11-02-10, 02:43 AM
looking good sven914
the amber does turn on when car is turned on but then it switches to the green one. mine does that too.
whats wrong with the amber? Saw that it never turned on?

sven914
11-02-10, 08:53 PM
^The wire I used has too much resistance, so the amber bulb looses its ground after a minute. When I get around to it, I'll rerun that wire with one of a smaller gauge.

1980coupe
11-08-10, 01:29 AM
hey, now my fuel economy lights are malfunctioning; well just the green one. First the amber wouldn't turn on but the green did, so now the amber lights up when ignition in "on" but the green one does not light up. I have my service manual with me and can't quite understand it what it means to "ground economy switch" I bought new bulbs too and the green does not turn on. Vacuum is fine, so maybe economy switch?? Would have to go to the yard and check out the white 80 Coupe thay have there and the 77 Fleetwood I saw on Thursday..to see if they have those economy switches, I have one so I'll checked that out

1980coupe
11-08-10, 02:37 AM
this is what it reads in service manual
Diagnosis
FUNCTIONAL TEST
1. Turn ignition switch to "ON" position and ground each terminal at economy switch. Both amber and green indicators should glow. If not, check for burned out or missing indicators bulbs.
2. Turn ignition switch to "ON" position; amber indicator should glow. (it does)
If not, check for loose or disconnected wires at fuel economy switch or poor ground. (all good)
If none of the above correct operation, replace switch. (have another to test)
3. Start engine and allow to idle. Green indicator should glow. (doesn't)
If it does not glow, check for a plugged, kinked or leaking hose between fuel economy switch and vacuum source. Check for loose or disconnected wires at fuel economy switch or poor ground. (all said is fine) If none of the above correct operation, replace switch. (have another, will test that one)
I'm thinking it's the printed circuit that could be the problem. The amber light housing was loose and wasn't making a good contact but the printed circuit around it looks pretty beat up. Will test out other switch I have this morning....if not back to the yard!!

sven914
11-08-10, 12:13 PM
^You can use any '80's printed circuit and just switch over the two multi-pin connectors to the new one.

Another thing you can do is get a 12 volt test light (they sell them cheap at parts stores) and see if the ground on the economy switch is changing from the amber to the green. To do that, connect the test light to battery voltage and touch the other end to one of the prongs on the economy switch. The one that makes the light illuminate when the engine is off is the one going to the Amber indicator. Do the same thing with the engine running and the other prong should make the light come on. If the test lamp lights on the other prong while the engine is running, but the Green indicator isn't on, then there is a broken wire in the green indicator circuit. If the test light does not light on the Green prong or still lights on the Amber prong, with the engine running, then the economy switch is dead and needs replaced.

1980coupe
11-08-10, 10:24 PM
^You can use any '80's printed circuit and just switch over the two multi-pin connectors to the new one.

Another thing you can do is get a 12 volt test light (they sell them cheap at parts stores) and see if the ground on the economy switch is changing from the amber to the green. To do that, connect the test light to battery voltage and touch the other end to one of the prongs on the economy switch. The one that makes the light illuminate when the engine is off is the one going to the Amber indicator. Do the same thing with the engine running and the other prong should make the light come on. If the test lamp lights on the other prong while the engine is running, but the Green indicator isn't on, then there is a broken wire in the green indicator circuit. If the test light does not light on the Green prong or still lights on the Amber prong, with the engine running, then the economy switch is dead and needs replaced.

About the printed circuit, that I know. This morning I removed the economy switch and bolted the other and it did the same as the one I removed. Amber lights up with ignition "ON" and with engine running goes out to but the green is not on but on heavy acceleration the amber comes on and both economy switches I have did the same. So today in the afternoon before heading out I messed with it some more; removed dash and messed with the indicator light and it light up (green one) Engine running. So with that it led me to suspect that IT IS the printed circuit and by the looks of it; the one for the green light is all messed up. It doesn't have enough of the circuitry to go around the perimeter of the hole thus not making good enough contact. So this Thursday will head out and get me another and take my service manual on how to remove the printed circuit. But for right now it has been fine. Both indicators responding accordingly.

sven914
11-09-10, 01:07 AM
^The bulb for my check engine light does the same thing if it's not screwed in right. But I can feel the car change between open and closed loop, so I don't need that light to tell me it happened.

gdouaire
10-11-14, 05:37 PM
Awesome thread. Noticed these indicators in my 1981 Service Information manual, but nothing was documented in terms of wiring...

gdouaire
10-13-14, 06:09 PM
As for my case, found a vacuum sensor on eBay and will install it in my 1981 Cadillac. Just because it looks like a fun game to play - switching between the amber and green lights while driving.

Adrian12
10-14-14, 08:20 AM
see information on this link :)

http://www.cadillacforums.com/forums/cadillac-seville-cadillac-eldorado-forum/204977-fuel-economy-indicator-lamp.html

bigm57ict
10-14-14, 10:19 AM
My '79 has this option.
Mine lights up green most of the time. It takes a pretty heavy foot to switch it to amber.
Maybe it's because that 425 pulls so effortlessly, even with my fairly aggressive driving style.

----------

The fuel monitor option was about $31 in 1979.
I guess that just pays for that little vacuum switch since everything else is there already.

gdouaire
10-14-14, 11:24 AM
As mentioned somewhere else in this thread several years ago, the 1981 Cadillac 368 already has the "MPG sentinel" which can display instantaneous fuel average - so the green/amber light holes were present in the dash PCB and the facia, but not wired and no vacuum sensor either.

the APEMAN
10-14-14, 02:11 PM
They need an idiot light that says "your wife is about to hire a lawyer".

gdouaire
10-22-14, 08:54 PM
Got the sensor in the mail. Now need to wire this so that it looks stock - right wire colors, etc.

gdouaire
10-23-14, 05:38 PM
And, for future reference, here's how to mount the vacuum switch to make it look stock-ish.

Actually mounted near the center bulkhead connector on the cowl.

bigm57ict
10-27-14, 10:00 AM
Here is what it looks like installed in my '79:

http://i1284.photobucket.com/albums/a579/bigm57ict/IMG_20141025_115830_241_zpsc01b3629.jpg (http://s1284.photobucket.com/user/bigm57ict/media/IMG_20141025_115830_241_zpsc01b3629.jpg.html)