All kinds of electrical problems - single cause?
Thread Starter
Heel & Toe
Joined: Feb 2008
Posts: 21
Likes: 0
From: CA
All kinds of electrical problems - single cause?
Hi All,
My 89 coupe, that I bought new in 89 and drive every day, is having a little electrical problem. It started a few days ago when I plugged my cell phone in the cigarette lighter to charge - no little red light on the plug. Then I noticed no temperature showing on the heating/AC controls and they don't work. Then I noticed no time display on the radio and the radio didn't work when turned on. I've since noticed no warning chimes for any reason - although the "Door open" warning light displays, no courtesy lights in the footwells or behind the seats - the light under the rearview mirror works.
When I turn on the headlights the "Fasten Seat Belt" light comes on and stays on - it doesn't come on when I start the car. The instrument cluster display works fine and the engine runs fine. So, I originally thought maybe a bad earth, but that wouldn't explain the "Fasten Seat Belts" sign. Perhaps a chafed wire or two? One more thing, I replaced the battery about a month ago, not sure if this is relevant. I'd really appreciate some suggestions on where to start troubleshooting this.
Thanks,
Tony
My 89 coupe, that I bought new in 89 and drive every day, is having a little electrical problem. It started a few days ago when I plugged my cell phone in the cigarette lighter to charge - no little red light on the plug. Then I noticed no temperature showing on the heating/AC controls and they don't work. Then I noticed no time display on the radio and the radio didn't work when turned on. I've since noticed no warning chimes for any reason - although the "Door open" warning light displays, no courtesy lights in the footwells or behind the seats - the light under the rearview mirror works.
When I turn on the headlights the "Fasten Seat Belt" light comes on and stays on - it doesn't come on when I start the car. The instrument cluster display works fine and the engine runs fine. So, I originally thought maybe a bad earth, but that wouldn't explain the "Fasten Seat Belts" sign. Perhaps a chafed wire or two? One more thing, I replaced the battery about a month ago, not sure if this is relevant. I'd really appreciate some suggestions on where to start troubleshooting this.
Thanks,
Tony
Burning Brakes
Joined: Nov 2008
Posts: 995
Likes: 1
From: Naples Campania
Sounds like a power surge to me.
Check fuses. The bulbs might have just been old and blew when you put in a new battery.
Yes, most surges come from the alternator.
Yes, a new battery can cause one.
New battery is more efficient. Think of the system like a series of pipes. The coupler (battery) on a pump (alternator) blows out. You replace it. It flows more efficiently than before. The older piping is corroded. It cannot take the new higher pressure, even if it is what it is supposed to be. Sections of the pipe blow out.
Inspect and replace the bulbs and run through the fuses.
Check fuses. The bulbs might have just been old and blew when you put in a new battery.
Yes, most surges come from the alternator.
Yes, a new battery can cause one.
New battery is more efficient. Think of the system like a series of pipes. The coupler (battery) on a pump (alternator) blows out. You replace it. It flows more efficiently than before. The older piping is corroded. It cannot take the new higher pressure, even if it is what it is supposed to be. Sections of the pipe blow out.
Inspect and replace the bulbs and run through the fuses.
Safety Car
Joined: Apr 2011
Posts: 3,660
Likes: 22
Go thru the fuses first. Do the obvious.
Then look at the power source and grounds. All of your accessory power comes from the jumper post behind the battery. Not the actual battery terminals. Look at the post and if necessary test the fusable links to those post connections, under the battery tray.
C4 wire is famous for rotting and degrading. Look at the bulkhead plug behind the battery. Lots of display things and other related wires plug in at that big connector. Just see what kind of shape its in.
The big bulkhead seal on the passenger side firewall is only a seal for the harness that enters the cabin but it may offer a clue to the condition of the wire.
grounds are often responsible for mystery failures like this. You have MANY...so consult your FSM to locate the related system grounds.
Then look at the power source and grounds. All of your accessory power comes from the jumper post behind the battery. Not the actual battery terminals. Look at the post and if necessary test the fusable links to those post connections, under the battery tray.
C4 wire is famous for rotting and degrading. Look at the bulkhead plug behind the battery. Lots of display things and other related wires plug in at that big connector. Just see what kind of shape its in.
The big bulkhead seal on the passenger side firewall is only a seal for the harness that enters the cabin but it may offer a clue to the condition of the wire.
grounds are often responsible for mystery failures like this. You have MANY...so consult your FSM to locate the related system grounds.
Thread Starter
Heel & Toe
Joined: Feb 2008
Posts: 21
Likes: 0
From: CA
I really appreciate everyone's input, I was sure it was a grounding problem somewhere so you saved me a ton of time.
Tony in CA
