Author Topic: Digital Dash in a 1991 Fleetwood  (Read 2741 times)

Offline QuirkyCadGuy

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Digital Dash in a 1991 Fleetwood
« on: December 03, 2012, 10:34:07 PM »
I just purchased the prettiest little 91 Fleetwood. By most accounts, it's a perfect one owner low mileage(???) little Caddy. The only thing is, the digital speedo, fuel data center, and electronic climate control displays do not work. Everything else in the car functions properly. I've checked the obvious fuses and relays and all seem OK. I am guessing the cluster is bad, but would that cause all three displays to fail? Am I looking at an easy fix or did I get myself into trouble? I have a couple other Cadillacs with digital dash displays, but have never had any troubles. Any guidance would be appreciated.
James Rouillard
CLC#27327
1978 Seville Diesel
1985 Seville HT4100
1991 Fleetwood 4.9
1992 Brougham 5.7
1993 Fleetwood Brougham 5.7
2010 SRX 3.0

Offline Payton1960

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Re: Digital Dash in a 1991 Fleetwood
« Reply #1 on: December 03, 2012, 11:29:26 PM »
Common problem google digital dash repair lots of people fix them easy to take out.

Rick
Rick Payton -President
Central Texas Region Cadillac & LaSalle Club

1959 Cadillac Eldorado Brougham #56
1958 Cadillac Eldorado Brougham #590
1955 Cadillac Eldorado
1955 Cadillac Coupe Deville
1955 Cadillac Series 62 Convertible
1956 Cadillac Eldorado Seville
1968 Cadillac Eldorado
2000 Aston Martin DB7 Convertible
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Offline Gene Beaird

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Re: Digital Dash in a 1991 Fleetwood
« Reply #2 on: December 04, 2012, 08:08:41 AM »
I'm not certain what the issue is with your Fleetwood, but on the 94-96 Caprice/Impala, the connectors to the digital dash can get some corrosion on them.  The fix is sometimes as easy as unplugging the instrument cluster, and cleaning the connectors (both sides) with a No. 2 pencil eraser. 

I hope yours is as easy.

Gene Beaird,
1968 Calais
1979 Seville
Pearland, Texas

Offline Guidematic

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Re: Digital Dash in a 1991 Fleetwood
« Reply #3 on: December 04, 2012, 08:40:41 AM »

 If one display goes out, possibly it ,ay be a connector issue. However if they all go out, then it may be something like a power supply problem.

 I have seen this same issue in the Eldorado, where in the case of my Eldorado it was the Central Power Supply. I don't have the manual for these cars, so I can't shed any more light on it. It would be a good idea if you obtained the manual. Without it, electrical issues are next to impossible to diagnose.

 Mike
1970 Fleetwood Brougham 68169
1985 Eldorado Coupe 6EL57
1988 Eldorado Biarritz 6EL57
1990 Brougham d'Elegance 6DW69
1994 Fleetwood Brougham 6DW69

Offline 936CD53

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Re: Digital Dash in a 1991 Fleetwood
« Reply #4 on: December 04, 2012, 04:22:01 PM »
James, does your car have the original radio installed, and if so, does the display work? The digi dash, fuel data panel, climate control panel, and radio are all connected to the Body Computer Module VF (vacumn-flourecent) dimming circuit. Do the displays always stay dark or do they flicker? All are power by fuse 7 under the left side of the dash, and all are grounded at G101/100 near the battery. I may be able to help more knowing the answers to above. Service manuals are wonderful things!

Craig
Craig Brillhart CLC# 26217
1993 Sedan deVille Spring Edition Carmine Red White Top
1993 Sedan deVille Spring Edition Triple Black

Offline Dave Shepherd

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Re: Digital Dash in a 1991 Fleetwood
« Reply #5 on: December 04, 2012, 06:12:06 PM »
The usual circuits should be checked as suggested, but also as mentioned this was a chronic problem with these digital displays, ther are several companies that repair them or exchange for rebuilts.

Offline QuirkyCadGuy

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Re: Digital Dash in a 1991 Fleetwood
« Reply #6 on: December 04, 2012, 06:51:39 PM »
@Craig. The car does have what appears to be the Factory Stereo. If it has been replaced, it was replaced with a Cadillac Stereo. When I purchased the car yesterday, the digital displays did not come on at all, with the exception of the radio which is working normally. Today I actually replaced the BCM with a used one out of a 1993 Deville. When I did, the speedo came on an stayed on for aproximately 1 minute. The fuel data center flickered and danced for a few seconds and then went away. The climate control center came on and went out after only a few seconds. In very short time, the BCM became hot to the touch and smelled of burning plastic. I immediately quit fooling with it and unplugged the BCM. Figuring I had nothing to lose, I opened the BCM that I had just gotten hot. The second port from the left was melted. I then examined the one that came in the car yesterday and the same port is melted. So something and I don't know what is frying the BCM. I have read on another forum that there is some kind of central power supply that is known to cause trouble. So thats where I am today. Open to suggestions.
James Rouillard
CLC#27327
1978 Seville Diesel
1985 Seville HT4100
1991 Fleetwood 4.9
1992 Brougham 5.7
1993 Fleetwood Brougham 5.7
2010 SRX 3.0

Offline 936CD53

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Re: Digital Dash in a 1991 Fleetwood
« Reply #7 on: December 04, 2012, 07:37:15 PM »
James, obviously you have a more serious problem. Does the blower motor work? The BCM supplies 16 volts to both the VF displays and the blower control circuit. I'll have to dig in farther tomorrow when I have more time. I'd unhook the blower power module or the battery until you find the problem.
Craig Brillhart CLC# 26217
1993 Sedan deVille Spring Edition Carmine Red White Top
1993 Sedan deVille Spring Edition Triple Black

Offline QuirkyCadGuy

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Re: Digital Dash in a 1991 Fleetwood
« Reply #8 on: December 04, 2012, 08:41:40 PM »
Climate control is non responsive so I'm not sure if the blower motor works.
I think I'm looking at a dead short somewhere. Tracing it is gonna be a bear. The car is so nice so I'm not giving up. Engine cooling fan comes on sometimes when you turn on the key but not every time. Not sure if that makes a difference. When I say the port is melted, it's not at the plug. It's on the inside at a spot where three wires marked B C and E are marked on the circuit board. I'm sure this sounds like gibberish, so if anyone wants a pic, I can send.
James Rouillard
CLC#27327
1978 Seville Diesel
1985 Seville HT4100
1991 Fleetwood 4.9
1992 Brougham 5.7
1993 Fleetwood Brougham 5.7
2010 SRX 3.0

Offline 936CD53

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Re: Digital Dash in a 1991 Fleetwood
« Reply #9 on: December 05, 2012, 01:14:47 PM »
James, unfortunately there is no internal schematic of the BCM in the service manual. Can you trace the circuit back to the connectors and identify the connector and pin #? connector C1 pin a9 goes to the blower power module, for example. The Power module is a frequent issue on these cars. It has 2 connectors and a large aluminum heat sink,  and is on the firewall on the right side of the engine compartment. I strongly suspect that is what is frying the BCM and making the displays inop, but more tests are in order. Another word of caution, IF the power module is diagnosed as the fault, replace the blower motor at the same time. In almost every case i have seen, failure of one of them takes out the other one.

From your description, I suspect the internal bcm part tha is fried is the solid state voltage regulator....
Craig Brillhart CLC# 26217
1993 Sedan deVille Spring Edition Carmine Red White Top
1993 Sedan deVille Spring Edition Triple Black

Offline QuirkyCadGuy

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Re: Digital Dash in a 1991 Fleetwood
« Reply #10 on: December 05, 2012, 06:11:29 PM »
 :Craig. Picked up a new used power supply and another BCM. Disconnected the blower motor. Hooked up the new power supply and the new BCM. Pretty much same results as yesterday. Climate control lit briefly and never came back on. Fuel data came on and stayed on  but the numerals began to dance around. Speedo disPlay came on and stayed on. BCM started to warm up so I aborted the drill. What do you think?
James Rouillard
CLC#27327
1978 Seville Diesel
1985 Seville HT4100
1991 Fleetwood 4.9
1992 Brougham 5.7
1993 Fleetwood Brougham 5.7
2010 SRX 3.0

Offline Dave Shepherd

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Re: Digital Dash in a 1991 Fleetwood
« Reply #11 on: December 05, 2012, 06:13:34 PM »
Assuming good connections and grounds the cluster is bad, just like almost all of them failed at some time.

Offline 936CD53

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Re: Digital Dash in a 1991 Fleetwood
« Reply #12 on: December 05, 2012, 06:38:13 PM »
James, send me your email addy via private message, I'll scan the diagnostic pages from the service manual and email them tomorrow. Try diconnecting the ECP (climate control panel) and redo your test..

I am writing the authenticity manual for these cars..would you be willing to take some pics for the manual? I'd let you know specifically what I need.

BTW Dave and Mike here are the hands on guys for these cars, I was a cadillac service manager when they were new and am reciting some of these things from memory..and the service manual!!  :)
Craig Brillhart CLC# 26217
1993 Sedan deVille Spring Edition Carmine Red White Top
1993 Sedan deVille Spring Edition Triple Black

Offline Dave Shepherd

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Re: Digital Dash in a 1991 Fleetwood
« Reply #13 on: December 06, 2012, 08:19:48 AM »
James, send me your email addy via private message, I'll scan the diagnostic pages from the service manual and email them tomorrow. Try diconnecting the ECP (climate control panel) and redo your test..

I am writing the authenticity manual for these cars..would you be willing to take some pics for the manual? I'd let you know specifically what I need.

BTW Dave and Mike here are the hands on guys for these cars, I was a cadillac service manager when they were new and am reciting some of these things from memory..and the service manual!!  :)  Craig I was a field trouble shooter for Cad. in NYC in the mid 60's to late 70's, then left GM and became a Cad svc mgr for a multi line dealer on LI, NY, John Staluppi.

Offline QuirkyCadGuy

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Re: Digital Dash in a 1991 Fleetwood
« Reply #14 on: December 06, 2012, 09:32:43 AM »
So last night I traced the melted part of the BCM to the corresponding pins at the plug. Keeping in mind, that I am no electronics expert, this is what I found. A12, C3, C11, and C12 lead to the melted part of the BCM. I think the melted part is marked Q11. Does this make sense to anyone?

Thanks for all the input. I'm going to figure this out if kills me. I suspect the previous owner had these troubles and could not figure it out, so it was traded. It's clear there has been a lot of impatient activity behind the glove compartment.

Thanks
James "Jamie" Rouillard
James Rouillard
CLC#27327
1978 Seville Diesel
1985 Seville HT4100
1991 Fleetwood 4.9
1992 Brougham 5.7
1993 Fleetwood Brougham 5.7
2010 SRX 3.0

Offline Guidematic

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  • Name: M. Jones
Re: Digital Dash in a 1991 Fleetwood
« Reply #15 on: December 06, 2012, 09:48:19 AM »

 I saved my '88 Eldo from the wreckers. I later found out why. The dash worked fine when I checked the car out, but a little while later it began to act up. I got off lucky, it was the CPS which I found at a local wreckers for $25. 5 1/2 years later, it's still fine, and it's been a good car overall. Even if it is beginning to get a bit ratty of late.

 I feel a lot of these cars may have suffered similar fate because of this problem. It can really intimidate owners to either trade in or scrap the car.

 I'm sure some perseverance will locate the source of the problem.

 As a rule, these modules do not send power to any circuit, but only supply a ground path from the load, and only do so with small amperages. Larger amperages will use a relay that is triggered by the module. It is possible that one of these loads may be supplying full battery power through to the BCM, wherein it finds its' ground path resulting in a dead short that destroys the BCM.

 Trace back the circuits that relate to those pin #'s. You may find a cross circuit, a defective load. Again, where having the manual comes in very handy.

 Mike
1970 Fleetwood Brougham 68169
1985 Eldorado Coupe 6EL57
1988 Eldorado Biarritz 6EL57
1990 Brougham d'Elegance 6DW69
1994 Fleetwood Brougham 6DW69

Offline 936CD53

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Re: Digital Dash in a 1991 Fleetwood
« Reply #16 on: December 06, 2012, 03:56:00 PM »
Lets double check the grounds first. The negative battery cable has 3 leads coming out of the connector at the battery. One goes to G100 whic is the main engine/starter ground. one goes to G101 which is on the rt fender behind the battery, the main body ground. It will have several wires with it on a stud , make sure all the wires are clean and the connection is tight. The 3rd lead is the clean ground where ALL of the electronic modules are grounded, including the BCM, PCM, antilock controller, air bag controller, digital cluster, FDc, CCP etc etc. Near the battery you should find one large one wire connector, wit a larger gage black wire on the battery side and and equal gage black/white wire on the other side. Make sure that connector is clean and tight. Follow the harness back toward the firewall, in the conduit you should find splice 120, visually inspect that it isn't crawling with corrosion. there are at least 20 ground wires spliced there.

The terminals at the BCM you called out are A12 main ground. C3 door jamb input. c11 not used. c12 accessory(switched)power. I know how hard it is to see those numbers..what color(s) are the wires on the connector side? a12,b12, and c12 all go to the internal voltage regulator in the bcm, as do d13 and d15, and c13 and c15. D13 is the power supply for the VF displays. C13 is 5 volt reference for the FDC and CCP.

I still suspect the ECC power module. It is the only connection where 12 volts could get back to the BCM, via the blower feedback circuit. Inspect that connector for corrosion or being melted.
Craig Brillhart CLC# 26217
1993 Sedan deVille Spring Edition Carmine Red White Top
1993 Sedan deVille Spring Edition Triple Black

Offline Glen

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Re: Digital Dash in a 1991 Fleetwood
« Reply #17 on: December 06, 2012, 11:09:38 PM »
In electronics parts labeled with a Q are transistors. 

Transistors can go bad and short out. 

HTH
Glen Houlton CLC #727 
CLCMRC benefactor #104

Offline QuirkyCadGuy

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Re: Digital Dash in a 1991 Fleetwood
« Reply #18 on: December 09, 2012, 02:47:48 PM »
Well I do appreciate all of the input. I tried all suggestions, but couldn't trace it myself. So it's sitting in the shop of Kendall Cadillac. I don't feel too bad as they weren't able to diagnose right away either. Hope to hear something on Monday. Will post results.
James Rouillard
CLC#27327
1978 Seville Diesel
1985 Seville HT4100
1991 Fleetwood 4.9
1992 Brougham 5.7
1993 Fleetwood Brougham 5.7
2010 SRX 3.0

Offline QuirkyCadGuy

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Re: Digital Dash in a 1991 Fleetwood
« Reply #19 on: December 16, 2012, 11:03:34 AM »
As it turns out, it was the electronic climate control digital display that caused my entire problem. Thanks to all for the suggestions. Craig B was right with his suspicion. He clearly knows about Cadillacs of this vintage.

Happy Cadillac"ing"
James Rouillard
CLC#27327
1978 Seville Diesel
1985 Seville HT4100
1991 Fleetwood 4.9
1992 Brougham 5.7
1993 Fleetwood Brougham 5.7
2010 SRX 3.0

 



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