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New question. 1991 Cadillac Deville. A couple of body

electrical problems. Erratic Fuel gauge...
New question. 1991 Cadillac Deville. A couple of body electrical problems. Erratic Fuel gauge. The Heat / Cool flap module doesn't activate (the motor works fine) and where the heck is the fuse for the motorized outside mirrors?
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Customer reply replied 1 month ago
Mirrors. My wife was trying to move them after a very cold snow storm. Both were frozen, yet she continued. Then both quit. I've replaced the joystick switch in the arm rest twice. nothing. It's a bit strange both would quit at the same time if it isn't a fuse.
Customer reply replied 1 month ago
The erratic fuel gauge. It reads E or sometimes jumps to 3 gal or full. Now it's been E for 3 weeks. I've just had the entire fuel pump and sender unit replaced twice. The first time was to fix the pump. Then when the gauge didn't read correctly, they replaced it with a second pump / sender unit under warranty. I heard that sometimes the eeprom needs to be removed from the socket, contacts cleaned and put back in. If the flap module is also not working, could all this be a bad computer? Like the BCM?
Answered in 1 hour by:
3/9/2018
roybelding
roybelding, ASE Certified Technician
Category: Cadillac
Satisfied Customers: 7,287
Experience: 35 years of retail operations working on all vehicles.
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hello, my name is ***** ***** I will be glad to assist you. please allow me a couple of minutes to gather some basic info.

Roy

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Customer reply replied 1 month ago
Hey Roy. You helped me with steering column yesterday. Turns out the lock plate went in the opposite way. Good now

thats an aftermarket switch which most likely is an addon. could be a kill switch that was installed.

Roy

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Customer reply replied 1 month ago
Just getting the airbag and horn back in. As soon as it’s tight, I’ll hook the battery back up and see if that explodes lol
Customer reply replied 1 month ago
Then I’ll start work under the dash with the computers. If I replace the entire BCM, that doesn’t deal with the performance chip correct?

correct.

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in case you need a bcm

https://www.rockauto.com/en/catalog/cadillac,1991,deville,4.9l+v8,1025716,electrical,body+control+module+(bcm),2888

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any update

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Customer reply replied 1 month ago
Finished with the steering and the driver side dash repack. Have a show to produce tomorrow so we’ll be out all day and night. Back on it Sunday. Is it worth trouble shooting the individual issues or just get a new BCM and see how much gets fixed.

you will need a scope to test. no volt readings as part of a diag.

Roy

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Customer reply replied 1 month ago
Hey Roy. Sorry for the delayed response. As in scope, are you saying some type of auto diagnostic tool or a meter for volts, ohms...etc. I think at this point, I'll pull the BCM, see if it has that eeprom in a socket, pull the chip, clean the contacts and re-seat. In the meantime there is a chain of salvage yards here in Boise that have always provided good parts. If I can't find one there, I'll order a new one.

you can try that. make sure the numbers are exact.

Roy

Please take a moment and rate my service 3 stars or better. that is the only way the site will pay me for my efforts.

Roy

roybelding
roybelding, ASE Certified Technician
Category: Cadillac
Satisfied Customers: 7,287
Experience: 35 years of retail operations working on all vehicles.
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Customer reply replied 1 month ago
to finish the inside work, the remaining issues are: Fuel Gauge read out (since reconnecting the battery, it just shows an "L" on the milage side and "E" on the fuel level side). I saw there was a reset / reboot process involving turning the key off, removing the fuse for the BCM...that type of stuff. Also, there is some type of combinations of holding certain buttons down on the environmental control that resets some things. Any thoughts on that? Thanks
Customer reply replied 1 month ago
Next is the heat / cool flap actuator. I've replaced that whole unit one time before (years ago). I took this unit out, opened it and ran 12v DC to the motor and it works fine. I don't see any burnt components in the box and all the connectors are clean. Could that be a failed box component or also having to do with a buggy BCM?

the only thing you can read is the engine codes from the display.

hold the off and warmer button together and it will display codes. e codes are engine f codes are body.

resetting does nothing unless repairs are made. after the ecm or bcm sees the correct readings it clears the codes on its own.

Roy

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the heat/cool is controlled by the programmer on the side of the heater case. a common failure was the motor inside the programmer for the mode door. did tons of them for that failure.

Roy

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Customer reply replied 1 month ago
a full BCM replacement sounds the most logical? If so...that's fine.

thats where I would start

Roy

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Customer reply replied 1 month ago
If the motor does spin with direct current to the + - poles (not the other little motor mount 3 pole thing, is that not an indicator the motor is fine?

it needs to spin in both directions

Roy

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Customer reply replied 1 month ago
I also tested the motor in the unit I pulled out years ago. I still had the entire box from that. Again the motor ran fine, yet when I replace the entire box, it worked. The motor does spin both directions when I simply reverse the 12V DC when I'm testing. So I guess it's either components in the box or again, the BCM. The Environment panel all works fine

yep, I agree

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Customer reply replied 1 month ago
Also, the schmatic you sent for the mirrors seems to be related to the system that turns on the anti-glare features. I'm looking for the motorized part of the system. Both mirrors quit at the same time when my wife was trying to adjust them on a cold day when the was frozen snow packed in them. That would say fuse to me. I've replaced the joy stick a couple of times. Nothing. The only fuse indicated in the main under-dash fuse panel is for the heating circuit on the mirrors...nothing about the motors or adjusting the mirrors
Customer reply replied 1 month ago
you agree? More likely the BCM or the circuits in the box the motor is mounted in? Those actuator boxes are pretty cheap and there's a ton of caddy's at the pick a part yard

let me check again

did you check for power to the joystick?

Roy

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I think part or most is related to the bcm.

Roy

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Customer reply replied 1 month ago
I tried...I think. There's a lot of wires going to the joy stick plug. Should I check a certain wire to ground or a certain wire to another certain wire?
Customer reply replied 1 month ago
I guess I need a diagram for the mirror motor control not the heated or anti-glare circuits.
Customer reply replied 1 month ago
Ah...ha! The 15A fuse is in the relay center! I'm assuming that is either the fuse panel down by the right kickboard on the passenger side or the firewall mounted panel in the engine compartment. The drop down panel under the dash on the drivers sde doesn't seem to have any relays on it.
Customer reply replied 1 month ago
OK. That helps. so at this point, I'm going to leave you alone...you've been great and justanswer.com will be charging me for my first full month so I guess that starts some cashflow your way. Plus I see the "tip" option which I'll get on. I'll be finishing up all this electrical work tomorrow I hope when I can get a flap control replacement module after I get a new BCM and see if everything clears up. You're now my main dude as I go forward with my commitment to breath new life into this vintage Crapillac...thanks.

thanks.

the site gets all the money. we are sub contractors who get a small portion of what the site charges you.

Keep me updated

Roy

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Customer reply replied 1 month ago
Oh yeah. Next on the list is the upper and lower oil cooling hoses. They are leaking pretty good but funny, I only see one hose not two when I look online for new ones. To be clear, are the two metal / rubber hoses that go into the top and bottom of the radiator on the drivers side the oil cooler? Not sure why I only find one replacement hose. Or is that transmission? It's definitely oil coming under the car not tranny fluid. some say valve cover gaskets which I'll replace also, but only seeing one replacement hose is weird
Customer reply replied 1 month ago
Oh...it's not tips...it's bonus. I'm assuming that is extra to you? Let me know on the hoses and I'll post some pics in a little bit. Thanks Roy. Where in NY? We are moving back home to Boston next month. We've been in Boise since 1991

you have transmission cooler lines and oil cooler lines. the oil cooler lines come off the oil filter if I remember. then they go to the radiator.

I am in harrisburg pa. I travel all over the country teaching this on site to techs.

Roy

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Customer reply replied 1 month ago
Cool. More to come. Gave a great Sunday.

you as well

Roy

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Customer reply replied 1 month ago
Good morning Roy. Today's project is the oil leak. It appears to be from these two hoses (upper and lower) that come off the upper and lower driver side shoulder of the radiator. The attached image shows different views. Question: Why when I go on line looking for the two hoses...for this model of Cadillac it only shows 1? I think it's called the oil cooler inlet hose. Inlet to what? Oil to radiator or radiator to oil. They both head back to around the oil filter housing. My oil levels are what go down...not the tranny. The spot is fresh oil. Let me know. Tom
Customer reply replied 1 month ago
No big rush as the moment. I'm busy for a couple of hours. I'm going to pull the BCM this morning, remove the eeprom and clean the contacts as once was suggested. Try a couple of thoise type options before I get a new one.

the one on the left is the upper coolant hose

the center and right side is the transmission cooler line. they go back to the transmission itself.

Roy

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Customer reply replied 1 month ago
seeing my tranny levels have remained topped off and the spot on the ground is oil, I'm assuming any fluids in there are dripping to the lowest point and then going to the ground.

very possible. I would take the car to a self serve car wash and clean it all off on the engine and trans. then watch for the leak

Roy

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Customer reply replied 1 month ago
I did that once and took it to Meineke. They said the oil cooler hoses (plural) and possibly the valve cover gaskets also. They wanted $800 to R&R. Their quote showed two hoses and that's why I was scratching my head when I only see 1 online. That's the kind of coin when I say DIY. Do you have a good diagram of the oil and tranny cooling lines? Thanks

let me check

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Customer reply replied 1 month ago
does the tranny cooler use the smaller radiator in front of the main radiator?
Customer reply replied 1 month ago
thanks to RedNeck youtube repair (known for their excellent camera handling and heavy southern drawl) this is showing a two hose combo as used in many 90's GM cars. Does this look like the part? https://youtu.be/7MiM0TcDcBA?t=4m

if those lines go back to the trans, yes. if not that may be the power steering cooler. GM was all over the place with coolers.

the trans cooler may be in the radiator. see if the lines go into the radiator.

Roy

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thats a much newer set up. you had 2 lines coming off the oil filter housing at the top of the motor and then up front

Roy

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Customer reply replied 1 month ago
Yeah...and all in a very small space. So this is what I found for a diagram and a site that lists both the inlet and the outlet parts which is the first time I've seen both hoses. https://www.1aauto.com/1991-cadillac-deville-engine-oil-coolers/y-mo-c/1991-269-120

yep, 7 and 15 are the oil cooler lines

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good deal, love that place

Roy

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Customer reply replied 1 month ago
FYI. I took out the BCM and removed the eeprom and cleaned all the contacts in the socket and all the legs on the chip. I put it back in and plugged in the BCM and voila...the Fuel center went from "L" and "E" to registering instant economy and 15 gallons (I had recently filled it) Now I'll put a replacement flap activator module in and see where we stand. But the fuel center coming back alive is a good thing

good job

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Customer reply replied 1 month ago
Hey Roy...hope your week was good. So I reassembled the entire dashboard once I cleaned and reseated the eeprom and also got a new heat / cool mixer activator. Everything works fine. When I started the car, the fuel gauge went from "L...E" to "0...5" indicating that the average MPG was reset but it was now reading the actual amount of fuel in the tank. I filled it up and the gauge went up to "F" which seemed to say it was working. After a few days of local driving (130-150 miles) it still has not come down off of "F" (which I believe now instead of indicating FULL, now means the other F word!) Seeing that the eeprom re-seating made some type of difference, but now the gauge is still non-responsive, do you think it's still the BCM and it needs to be completely replaced?
Customer reply replied 1 month ago
Now...I'm back under my wifes 1992 F350 IDI with turbo and having to probably replace the clutch slave cyl. A very basic question. The master fluid tank was empty. The clutch was working great but during a 15 mile trip, it went from fine to nothing gradually. I do not see any fluid around the master cyl either on the outside or inside the firewall. My guess is at this point, it's the slave. I bought both parts. Would it be smart to start by replacing the slave in anticipation that it developed the leak and see if we regain function? Then replace the master if it's still not working? There is only one thing I hate worse than working under that beast is working under the dash

sorry, was traveling today.

replace them both together since you have them

Roy

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Customer reply replied 1 month ago
Back to the Caddy. A guy named Wayne is helping me with the F350. So...
18 March 2018 10:40Hey Roy...hope your week was good. So I reassembled the entire dashboard once I cleaned and reseated the eeprom and also got a new heat / cool mixer activator. Everything works fine. When I started the car, the fuel gauge went from "L...E" to "0...5" indicating that the average MPG was reset but it was now reading the actual amount of fuel in the tank. I filled it up and the gauge went up to "F" which seemed to say it was working. After a few days of local driving (130-150 miles) it still has not come down off of "F" (which I believe now instead of indicating FULL, now means the other F word!) Seeing that the eeprom re-seating made some type of difference, but now the gauge is still non-responsive, do you think it's still the BCM and it needs to be completely replaced?

could be the sender unit not functioning or the bcm.

Roy

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Customer reply replied 1 month ago
I had the entire gas tank removed and the entire pump and sender unit replaced last summer. They flushed the gas tank while they we at it. I got the car back and the gauge was not reading correctly. I took it back and they replaced the pump and sender again and it still doesn't show correctly. It was at that point I saw somewhere that reseating the chip was a resolve. Either it needs a real contact scrub or there is another issues. Please advise. Thanks. Tom

This is beyond cleaning at this point. I would consider replacing the bcm at this point

Roy

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roybelding
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