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Pete
Pete, Cadillac Technician
Category: Cadillac
Satisfied Customers: 24657
Experience:  17 years Cadillac experience as a technician.
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88 CADY DEVILLE NO POWER TO RELAY THAT SENDS 12V TO ALT SO

Customer Question

88 CADY DEVILLE NO POWER TO RELAY THAT SENDS 12V TO ALT SO NO CHARGE NO SPEEDO NO BAT LIGHT NO CLIMATE CONTROL NO FUEL DATA CENTER DOOR LOCKS MOVE AND CLICK BUT ALL DOORS DONT LOCK WINDOWS MOVE REALLY SLOW HAVE REPLACED BATTERY AND ALTERNATOR CHECKED ALL FUZES IN MAIN FUZE BLOCK AND FUZES BEHIND GLOVE BOX TESTED RELAYS WITH 9V BATTERY AND OHM METER THEY ALL APPEAR TO WORK PROPERLY
WITH KEY ON HAVE POWER TO CLIMATE CONTROL THROUGH ORANGE W BLK STRIPE WIRE NO OTHER POWER COMING IN SAME WITH FUEL DATA CENTER
Submitted: 10 months ago.
Category: Cadillac
Expert:  Pete replied 10 months ago.

My name is ***** ***** I am a professional here at Just Answer. I noticed that your question had not received a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.

If you havent checked for any damaged or broken wiring leading to the relay or fuse panels this needs done first.If any wiring is found to be at fault the affected wiring will need repaired or replaced to correct this issue here.If this has already been checked and found to be o.k. let me know so we can continue from here.

If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service.You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.

Thanks Pete

Customer: replied 10 months ago.
this large group of electrical problems seems to be common on these years of caddys.i look the wiring over did a lot of testing.the car runs but makes a lot of noise seems to come from the smog pump when i used a mechanics stethoscope on the new alt &power steering pump.also replaced the tensioner and idler pulleys.the engine gauges don't work.when you add it all up a lot of electrical parts arn't working for no blown fuzes or relays.
Expert:  Pete replied 10 months ago.

You should have a red wire and a black wire at the alternator that should have 12 volts dc on them with the key on or off.You should also have a brown wire that has power on it with the key on at the alternator.Which of these wires do not have power on them?

Customer: replied 10 months ago.
no 12v to the internal reg on alt from relay mounted on firewall it is the larger gauge wire the smaller one going to reg has 12v as well as the main wire on back of alt that goes to battery.theirs no 12v going to the large wire that the relay connects to when the relay is powered to make the connection.problem seems to be inside passenger compartment.
Expert:  Pete replied 10 months ago.

My info on this model shows you get 12 volts one from the starter solenoid at the red wire to the starter,one on the black wire leading from the battery to the starter and then 12 volts at the brown wire leading from the 25 amp fuse 7.I dont see a relay in line with these signals here.Are you sure you posted the correct year and model vehicle here?I just want to make sure on this.

Thanks Pete

Customer: replied 10 months ago.
year and model are correct.was my dads car and a caddy shop replaced the motor many years ago he drove it for years with no problems and the gave it to my mom who drove it for years she said the antenna was clicking so she took it to the caddy shop and the mechanic pulled the glove box out and made the clicking stop.after that the speedo and gas gauge quit those were the things she noticed but their are a long list of electrical components that don't work. shes 90 and hasn't been able to drive for 3 or 4 years so shes not sure if they quit right after the repair of the clicking antenna.Ive only driven it to have the alt tested and back home. sorry it's taking so long but she is having a rough night.
Expert:  Pete replied 10 months ago.

No problem on the delays and I hope she is doing o.k.

Looking at the diagram info on it here I dont see any relays in line for the charging circuit.Is there a way you can check the wiring at the alternator to make sure you have the colored wires I have posted above then test these wires for the signals I have posted above so we can continue here,when you get a chance as there is no hurry for me.

Let me know,thanks Pete.

Customer: replied 10 months ago.
just the brown wire has no power key off or on the others are both 12v key off or on
Expert:  Pete replied 10 months ago.

O.k. with the key on does the no charge or charge light come on on the dash at all?

Customer: replied 10 months ago.
sorry about my mistake it is the small black wire to the alt reg that has no 12v key off or on.i tested so much stuff i got confused.their is no relay in that small wire.just did a retest.the others both have 12v off or on.from battery and starter
Expert:  Pete replied 10 months ago.

O.k.,that black wire comes directly from the battery itself with no intermediate connections.Trace this black wire back to the battery and see if you see any bulges in it or corrosion indicating it needs replaced and to see if there are any nicks or cuts that need repaired and that the connection to the battery positive for this wire is clean and tight.If you find a fault correct it and see how the vehicle operates from there and let me know.

Thanks Pete

Customer: replied 10 months ago.
got out my big magnifying glass and brightest headlamp and that small wire is dark brown and goes through the left hand side top of firewall with a big bundle of wires i ohm metered it to make sure it is the same wire.their also is a smaller bundle to the left going through the firewall.my 66 year old eyes just don't work like they used to.it has 00.9v at firewall and 00.9v at alt.
Expert:  Pete replied 10 months ago.

If this is in fact the brown wire and not the black or red wire this wire runs from the charge light in the instrument cluster and this light is powered by fuse 7 which is a 25 amp fuse.If this fuse is good and the charge light is not lighting up on the dash this will cause this issue here and it is usually the instrument cluster itself that needs removed and taken apart to replace the burned out charge light bulb.I have seen this bulb burn out before and causes a no charge issue which also can lead to other electrical issues inside the vehicle.I would check into this first here to see if the bulb or fuse needs replaced.

Thanks Pete

Customer: replied 10 months ago.
i think that is in the speedo cluster.i see they remove the top of the dash by removing some screws i tried to remove the vents next to the speedo but they started to crack.is their an easy way to get the vents out so i can remove the screws inside that attach the dash top?
Expert:  Pete replied 10 months ago.

If you look inside the vents there should be little catch tabs that need carefully pried or pushed to release the vents from the dash.Once these are pushed or pried then vents should pull out and remove from the dash itself then the screws and cluster can be removed.You might be able to remove the bulb yourself and obtain a new replacement bulb from a dealer or local parts store to correct this here.

Let me know if you need anything else and feel free to rate my help.

Thanks Pete

Customer: replied 10 months ago.
Put in new bulb . No battery light key on service soon ,stop engine oil,coolant temp fan.no other gauges work or high beam indicator .also both radiator fans turn on with key
Expert:  Pete replied 10 months ago.

I apologize for the delay.

Check fuse 7 which is a 25 amp fuse and make sure it is good.If found blown replace it and see if this resolves the issue here.If it is o.k. take a test light or multi meter and test this fuse for power across it with the key on or engine running.You might remove it and turn on the key and test one of the terminals the fuse seated into for power or 12 volts DC.Let me know what you come up with here.

Thanks Pete

Customer: replied 10 months ago.
12v at both sides of fuze with key on only.remove fuze 12v to only one terminal.replaced bulb it doesn't light key off key on motor running.pulled new bulb out after tests it is still good.
Expert:  Pete replied 10 months ago.

I apologize for the delay.

Do you see any issues with the wiring or connections at the instrument cluster at all?

Let me know so we can continue,thanks Pete.