Top 10 1999 Buick Century Questions & Answers

Iam an ASE Certified mechanic and i had the same problem with my 99 century and i wasnt able to drive at night. After hours of testing wires we came to the problem. Its the turn signal switch assembly which is tied into the hazard switch on top of the steering column. Its all one piece with a 3 foot long wiring harness attached to it running down the bottom of the steering column and going underneath the dash. The least expensive place i found the part and had it in stock was my local Auto Zone and still the part was $200.00.

P.S. This is a common problem on these GM cars. Mine did the same thing to the tee! The lights will go on and off then they just went off for good and this solved the problem. I guarantee it. If you have any questions please email me i will do all i can to help.

Philly, the fuel filter is attached to the frame in front of the gas tank, under the driver side of the car. You must relieve the pressure in the fuel line before you start, and it is also recommended that you disconnect the neg. battery cable. After disconnecting the neg. cable, remove the gas cap. Next, look under the hood on the fuel rail for a shrader valve (like the type on a bicycle tire). Place a rag under the valve, remove the cap, and press the valve in with a plastic pen to relieve the pressure in the line. You can now go under the car to remove the filter. You can disconnect the fuel lines easily with an inexpensive plastic disk made for this purpose (only a few $ for several sizes at a parts store). Be careful of fuel in the line that will drain out, no smoking or sparks during this procedure. Should be 1 bolt securing filter to frame. Note arrow on new filter, and install in the correct direction. Replace cap on shrader valve, put gas cap back on, reconnect battery cable. The low coolant light is probably a faulty sensor signaling that it's low, when it's actually ok. Look for wires coming from the reservoir bottle, you should be able to find the sensor at the end of the wires to replace it. If you change the fuel filter in a garage, leave the door open for air circulation, gas fumes can explode easily, having the door open will help dissipate the fumes.

I have been in the business for 35 years and have never seen a "brake line diagram". You easiest way to figure out which one goes to the right front would be to start at the right front caliper and follow it to the hydraulic control module.

Intake Manifold Coolant Pipe Bolt .... 89 in lbs (7.4166 ft. lbs)
Lower Intake Manifold Bolt .............. 115 in. lbs (9.5833 ft. lbs)
Upper Intake Manifold Bolt/Stud ...... 18 ft. lbs
Valve Rocker Arm Bolt ................... 168 in. lbs (14 ft. lbs +30 degress

Top left side of the engine, below the throttle body

open the passenger door fuse box located there.

this is a common problem and the dash cluster must be removed and sent out for repair, cost is about $175 to replace the LED (Light emitting diode) display that has burned out, this is a faxtory defect as far as this expert is concerned, it is not a fuse problem.

Your cooling sensor is in the white plastic coolant tank that is on your firwall under the hood. If you fill it with coolant and the light continues to stay on. try and slap it a few times and see if that resets it. it could be gunked up. if that doesnt work fill the tank with radiator flush and let it sit for a little while and then flush the tank and refill with coolant.

Under the glove box, there is a removable panel. pull the panel, to access the blower motor and the control / electrical wiring. The resistor looks like this------>>>> cost about $30.oo at most auto parts stores.

Both radiator fan relay's ????? There are three relay's !
DTC P0481Cooling Fan Relay 2 Control Circuit
Circuit Description
Output Driver Modules (ODMs) are used by the PCM to turn on many of the current-driven devices that are needed to control various engine and Transaxle functions. Each ODM is capable of controlling up to 7 separate outputs by applying ground to the device which the PCM is commanding on. DTC P0481set indicates an improper voltage level has been detected, which controls the Cool Fan 2 and Cool Fan 3 Relays.

Check cooling fan maxifuse 15 amp. This fuse supply's B+ voltage too cool fan relay's 2 & 3 control side . The PCM supply's a ground to energize these two relay's , the PCM is not seeing the correct voltage that it should be . The fuse could be the problem , an open circuit , the transistor or driver as GM calls it output driver module . The number 1 relay is working fine , with A/C on # 1 relay is turned on or energized by the PCM for low speed operation .
There is a good video on youtube on how this three relay cooling fan system works an how to trouble shoot .
Relay Driven Dual Cooling Fan Diagnostics