Car Repair Help by Professional Mechanics
Repair Topics
/ Electrical System-1
/ Electrical System-2
MORE: Electrical system
questions
Car Electrical System Questions and Answers - This category
contains featured questions as examples. They relate to most vehicles.
Question: 1988 Ford Ranger_mileage: 103,000. When I step on the brakes
the right directional's light up solid with the brake lights. The bulbs all seem
to be intact. Is it a ground? Is it a Switch? If so where?
Answer: You are apparently getting feedback from your brake light circuit
to the turn signal circuit. Verify that the taillight bulbs are the correct one
for your car. If your car is equipped with a wiring harness for a trailer verify
that it is not shorting out between connections.
Question: 2002 Chevrolet Silverado 6.0_mileage: 115,000. A few things
are happening: The odometer has gone back to zero, sometimes it will not come on
when the truck is started, and sometimes it reads error in the odometer read out.
The battery light also comes on some times and will not go off till I turn the truck
off and restart it. Also when the odometer does have mileage on it and not error
it will reset back to zero when the truck is turned off.
Answer: It appears that you have a faulty instrument cluster.
Question: 2002 Chevy Trailblazer LT Vortec V6 4.2_mileage: 60,000.
This problem is intermittent and I apparently haven't noticed all of the affected
components because I notice something new each day! My 02 LT is fully loaded
with 60k miles. A few days ago, the keyless entry didn't work. Immediately I assumed
the battery and replaced it the next day. I hit the unlock button and it still wasn't
working so I thought maybe the whole keypad was dead. I went home and tried the
spare...It didn't work either. I didn't put much thought into it until the next
day on my way to work it drizzled rain for a few miles. I turned the knob for my
rear windshield wiper and nothing happened. I pressed the button for fluid...still
nothing. I parked and turned off the engine after arriving at work and sat
there for a minute after realizing that my radio shut off when I turned the key
to off and I couldn't roll up my window. Under normal operating conditions, my radio
will play for 10 minutes, the windows will roll up/down and the interior light will
come on when the engine is OFF as long as the door has not been opened. I
was baffled. I went into work and when I came back out for lunch... (4 hours
later) I pressed the keyless entry...It unlocked! Got into the truck, turned on
the rear wiper...It worked! Came back from lunch, turned off the engine...radio
kept playing! This has gone on for about 1 week now. On/Off. I'm confused!
Is it a relay? I have searched the internet for HOURS looking for any kind of explanation...Chevy
dealer said it needs diagnostic and possible a new computer assembly switch. Please
help!!!! Thank you!!!
Answer: Based on what you have told us, replacing the
Body Control Module should fix your problem.
Question: 2000 Ford Excursion 6.8L V10_mileage: 120,000. The interior
lights and running board lights now stay on dimly during vehicle operation and for
25 minutes after vehicle is shut off or if you open and then close a door with vehicle
already shut off. There is no Door Ajar light, no Check Engine light and the
one code in the computer said pedal stop switch, which was replaced. Problem
remains. No drivability problems. A big hazard for my wife to drive
at night with all the interior lights on.
Answer: The problem with the interior
lights and running lights is probably due to a faulty generic electronic module
(GEM).
Question: 1989 Jeep Cherokee 4.0_mileage:
200,000. My son has a Jeep Cherokee that we have done a good amount of work to.
We are down to the last problem and are stumped. The alternator is putting out about
14 volts and the battery is steady at 12 volts. The volt meter in the dash reads
at best 12 volts and whenever any light or accessory is used it drops to below 9
volts. We have used a volt meter to check everything and we keep coming back to
a short. If you connect a voltmeter to between the negative post on the battery
and ground the other lead to the chassis it read 0 volts. Turn any lights or accessory
like the rear defog and the volts go as high as 6 volts. This would indicate a short.
Problem is we can not find it. It has to be in a main line because any item that
uses power adds to the short volts. Any help would be great
Answer: The first thing we would check, based
on the circumstances that you have described, would be the ground wires to see that
they are in place and making a good connection, especially the ones to the body.
Question: 1989 Pontiac Grand Am 6 cyl. mileage:
75,000 The other day I started the car and noticed the dash instruments do not work:
speedometer, tach, gas, temp... nor does the power windows, or the heater fan.
I checked all of the fuses, and they are ok. I cannot find anything that has
all of those functions in common, do you have any suggestions as to what it could
be?
Answer: The common function you are looking for
is the body control module.
Question: 2002 Chevy
Suburban 2500 mileage: 73,000. When you step on the brake, the #1 fuse blows which
not only controls the brake lights but also the flashers and buzzer. I spent 4 hours
at the Chevy Dealership yesterday. They checked the wire connections from under
the hood to the rear of the vehicle. They replaced the brake switch and the directional
switch located in the steering column with NO positive results. ANY IDEAS WHAT THE
PROBLEM MIGHT BE?
Answer: Most Suburban's were equipped with an extra wiring harness for
connecting trailer lights. Check out that harness as it may be causing your problem.
Question: 2002 Honda Accord mileage: 57,000. What conditions would short
the voltage regulator inside the alternator and at the same time blow the headlights,
interior lights, dash clock and damage the radio? The reason I ask is that after
I got my car back from the body shop from collision to right front of vehicle (passenger
side - battery side) they claim the electrical problems I now have were not a result
of the accident since the battery tray was not damaged? Does not sound right to
me. After further investigation the battery left cell was either shorted or somewhere
inside there is a break thereby making it "open circuit". Would the damage to the
voltage regulator have happened during the impact or during the trip home after
the accident? Currently the alternator is punching out 18V. A little insight here
would be appreciated.
Answer: Electrical problems are tough to troubleshoot. Check the wiring
harnesses for damage, especially the ground wires. Also, have the battery load tested
to be sure there is not a shorted cell inside. 18-volts from the alternator is too
high. This may be due to a missing ground wire or a faulty internal voltage regulator.
Question: 2001 Cadillac SLS. I am writing you today because of a problem
that started directly after my car was picked up from my mechanic last week. My
car was in the shop having the starter motor replaced, and I am sure you know, that
on my car you have to break down most of the top of the engine to get to it - what
a pain that project can be. I picked up the car and everything seemed all right
with it, until it became dark out. The background light on my tachometer and speedometer
were flickering. I started looking at things more carefully - I noticed that everything
was flickering: Headlights, interior lights, dash board (not digital stuff though)
and the best part is a random clicking noise like the turn signal noise is going
off but a lot faster - This happened over 1500 rpm. So I called my mechanic, and
explained to him what the trouble was and he suggested tightening all of the grounds
and changing a blinker bulb that had burned out. So I checked the grounds, and changed
the bulb. When I started the car after that I had no back light for the Speedometer,
Stereo, Shifter, dimmer switch and the left side running/tail lights for the back
of the car do not work, (But the brake lights do across the entire back end and
the Speedo also still works with no lights). So my question is, since all of these
accessories are not on one circuit/fuse line, do you think that the improper installation
of a Starter motor could cause these symptoms? Do you have any Ideas of what this
could be?
Answer: It is possible that an improper installation of the starter motor
did cause your problems. From what you have described it sounds as if the body control
module is failing. The main power wires have to be removed and reconnected when
the starter is replaced and if something were reconnected improperly, it would short
out the body control module.
Question: 2002 VW Jetta mileage: 34,000. I have a VW Jetta that I leased
in Sept 98. I am outside my bumper-to-bumper warranty. I have been experiencing
numerous electrical problems over the last 2 mos....possibly related I don't know.
The rear power windows only work sporadically.... when they decide not to work....
there is no noise...they just don't go down. A couple of times each week my coolant
indicator light comes on for a while then goes off. My coolant level has not been
low. There is no change in the temperature gauge...and no smoke/leaks/etc that would
indicate any problem w/the coolant level. My alarm activates itself on occasion
when I am driving. I know this because I'll be driving and I see the red light on
the driver side door lock start blinking as if the alarm is set...also the horn
beeps just as it does when you lock the doors from the outside and activate the
alarm. Furthermore, when this happens I cannot unlock the power locks unless I use
my keyless entry key chain (which doesn't work outside the car) inside the car.
That is the only way I can de-activate the alarm and unlock the doors. I have had
my vehicle into 2 VW dealerships, paid for diagnostics...and they tell me nothing
is wrong.... that the car is running to manufacture specs. I have been corresponding
w/VW customer relations as well. So far, no answers. Any suggestions?
Answer: Electrical problems can be extremely frustrating. We suggest checking
the wiring looms for damage or loose connections. Also check for poor ground connections.
You may have a faulty body control module.
Question: 1999 VW Jetta Automatic mileage: 50,000. My problem started
when my electric sun roof, dome light, and electric locks were not working.
My clock was also not working right; it came on, but did not keep the time.
It always goes back to 12:00 when I turn the car off. I checked the fuses;
one was blown, so I figured that was the problem. I had not replaced the fuse
yet, but when I got in my car yesterday, my speedometer and tachometer were not
working. I replaced the fuse (with the right size) and my dome light came
back on (it did nothing for the speedometer) but when I attempted to open my sunroof
the light dimmed and the fuse blew again. Any ideas? Are the two problems
even related?
Answer: It sounds as if both problems are related. There probably
is a short in the sunroof motor and/or the control switch for your sunroof.
Question: 2002 Toyota Camry miles: 78,900. Last past two years,
I have had problems with the electrical locks, seatbelts and windows. I believe
the problem my have originated in the driver's side panel. If I open the driver's
side to fast, the seatbelt will not go forward all the way. The passenger
side window does not go up or down at all. Now my car will not stayed locked.
If I lock it from the drivers side, when I shut the door it will unlock. If
I lock it from the passengers side it will stay locked, but not for long.
When I return to my car all the locks are unlocked. I do hear a clicking noise
in the panel just above the glove compartment when shutting doors.
Answer: About all you can do is to check wiring for damage and or
bad connections, especially the ground wires. There also may be a faulty switch.
Question: 1998 GMC Suburban mileage: 135,000. We have a GMC Suburban
1500 SLT, which has been great but has suddenly developed a strange electrical problem.
The remote keyless entry stopped working. When I checked the fuse box next
to the steering column, I pulled the appropriate fuse for that (which also controls
central locking) and it looked OK. But when I put it back in, it sparked and
wouldn't go back in. I can drive the car fine, but it is a pain without the
keyless entry and central locking. I'm guessing there's a short somewhere;
any idea where the likely place might be? Thanks.
Answer: Scan the body control module for fault codes. This should
pinpoint your problem.
Question: 2003 Toyota Camry mileage: 62,000. I was changing my alternator
with one from my 1985 Camry parts car. I forgot to disconnect my battery and
the alternator wire touched the engine and arced out. Now I have headlights
and horn but that is it. I have check fuses under dash in engine compartment
and fusible links near battery-circuit breakers. Could I have fried the computer?
Does it have a computer? When I turn the key on, all I get is the idiot "charge"
signal lit up. What to do? Thanks
Answer: Check the power distribution relays. You may
have "shorted" one.
Question: 1999 Chevrolet 4 WD mileage: 137,000. While driving down
the road, the gauges and speedometer quit working. No voltmeter, gas gauge,
oil pressure or temp. In addition, the service engine soon light does not
work. Scanner will not communicate. ECM fuses are not blown and
have power at them. Fusible links at back of alternator are not blown and
engine runs fine. Please try to assist me. Thank You. Baffled
-Elmer
Answer: Check for wiring damage and faulty ground wire connections.
Question: 1999 Chevrolet p/u 1/2 ton 4.3L mileage: 125,000. Second
time this has happened; the first time several months ago. I have been noticing
that when I crank the truck, it sounds like the battery is low or the starter is
dragging. Last night the speedometer and tachometer gauges were fluctuating
at a steady speed. When I would change from dim to bright lights, both gauges
would jump to the right about a half-inch and immediately return to the previous
state. Once the check engine light came on for a few seconds. This morning
the truck acted as though the battery was dead and I had to jump it. The battery
and alternator were checked out to be ok. Today the symptoms have all but
disappeared. There still is a little dragging when starting the truck, but
not as bad. Today I ran the truck with the lights on, radio on, and fan on
high, but no fluctuation of the gauges. The altimeter did seem to be little
further to the left of center than usual. Thank you for any ideas
Answer: Electrical problems are very difficult to find.
On your truck, we would check all the ground wires. From what you describe,
somewhere there may be a loose or bad connection. You said the battery checked
out okay, was it load tested?
Question: 1987 Nissan Stanza mileage: 130,000. We have
been having a problem with the electrical system in the car. The first symptom
was the instrument panel would go dead, the turn signals wouldn't work, no gauges
etc. Then the battery light would come on for a little while then the
seatbelt light would flash on then everything would start working again. No
bulbs are burned out. My husband has taken the whole thing apart and can find
nothing. (He's pretty mechanically inclined) We are completely stumped.
The only clue we have is that when you put the car in reverse there are no back
up lights and the battery light gets brighter. We have taken a voltmeter to
all of the wires in the steering column. Any clues?
Answer: Check the charging system and load test the battery.
Check the main power wires for bad connections. Also, check the ground wires.
Question: 1995 GMC (Jimmy) mileage: 74,000. I'm looking into a purchase
of this 95 Jimmy from a private owner. One odd thing is that the electronic clock
always stays lit. The owner said this has always been like that. Is
that true? All my other GM vehicles the clock shuts off when the ignition
is turned off. If I buy the vehicle as is, should I plan on a visit to my
local GMC dealer for a costly repair?
Answer: The light in the clock should go off with the key.
If the car is not driven for several days, the battery may go dead. We are
not sure why the light is on and have no idea what the cost of repairs would be
to trouble shoot the problem.
Question: 1997 Nissan 300sx mileage: 56,000. My car battery won't
hold a charge. It starts when I jump it, it will stay charged as long as I don't
leave key in the ignition or start it at least every four hours any more and its
dead, but like I said it starts right up with a jump. I had my battery tested
and its fine. Is this the alternator (which is 6 months old) or the starter?
Answer: If the car starts with a jump, the starter is okay. Was
the battery load tested with the proper equipment? You may have electrical
drain on the battery with the key off. Here is the procedure we use
to isolate a battery drain. Remove negative battery cable from the battery.
Using a 12-volt test light, hook one end to the negative battery post the other
end to the negative battery cable you just disconnected. The test light will
glow or "light" if there is a drain. If the "light or glow" is faint, that
is probably normal draw for the clock or computer. If the "light or glow"
is bright, then there is a large drain. That should be corrected. Now
start removing and replacing the fuses one by one until the light goes out; that
one will be the circuit with the drain. Remember to hold in the button in
the door jam for the interior lights.
Question: 1989 Chevrolet Suburban mileage: 136,000. I have an electrical
problem. I can't get the dash lights to work, and when I change the fuse,
it lasts about five minutes and then blows again. The buzzer would not shut
off, so I disconnected it. I need help and fast! PLEASE!
Answer: After a discussion, we think the problem may
be a short in the plug for trailer lights.
MORE: Electrical system
questions
Repair Topics /
Electrical System-1
/ Electrical System-2
Look up your electrical system question in our
Car Repair forum section.
Got Car Repair Questions?
We will answer it for FREE!
Related Subjects
GET ONLINE
CAR REPAIR MANUALS. Get instant access to your vehicles drive belt routing,
wiring diagrams, trouble code information, updates and factory bulletins.
| 
