1992 SAAB 900 not sure what the issue is.

LORIEANN1224

MEMBER
1992 SAAB 900
4 CYL
FWD
MANUAL
15,200 MILES

I lost two of three belts, power steering and waterpump, I replaced both, but have not replaced the airconditioning belt yet since I felt I did not need it right now. I started my vehicle and it sounded sluggish like low battery, but it started up. Had been running fine (a week or more) since replacing the belts. On the highway, after 30 minutes or so, my car started to get sluggish, then surged. The more I attempted to increase the gas, the slower she would go and she would buck. As I eased up, her power increased. However when I turned on my wipers, they too ran very slow, I had to shut all powersupplies off in order to get the car home, lights, wipers, blinkers, etc. My radio will not power up, and though I have charged the battery incase of low voltage, she turns over, but refuses to engage. My anti lock brake light came on as well as brake fluid, both are fine, could this be sensor? An electrical shortage? Please help, I would be more than happy to donate if your answer is able to aid me in getting my vehicle back up and running. Ty

3 Replies

CARADIODOC

MECHANIC
33,871 POSTS

Hi Ty. Welcome to the forum. Sounds like a charging system problem. That's what all of these things have in common. First, measure the voltage between the two battery posts with the engine not running. It should be near 12.6 volts. If it is around 10.5 to 11.0 volts, suspect a shorted cell in the battery. If it is around 11.5 to 12.0 volts, charge the battery at a slow rate for about half an hour. Next, measure the battery voltage again while the engine is running. It must be between 13.75 and 14.75 volts. If it is still around 12.0 volts, the generator is not working.

Caradiodoc

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Monday, April 19th, 2010 AT 4:50 PM

LORIEANN1224

MEMBER
2 POSTS

I had the car tested as you suggested. Was informed that I needed a new altenator. It was replaced, still no luck. I was told that the battery had been ruined because I had driven so far on the battery without building a charge, so I bought a new battery and cables. I am now experiencing the same issues as before. Starts with the antilock brake light coming on, then going off, using anything that draws on the battery such as wipers (very slow), lights, or blinkers, the car begins bring up the antilock light and the care begins to wane and stall. Trying to recharge the battery while hooked up (car is in the off ignition position) is impossible. The car will run as long as the jumper cables are attached. Once removed, the car will stall, and have no power to the battery. Fan blower is still almost non existant.

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Friday, April 23rd, 2010 AT 10:44 AM

CARADIODOC

MECHANIC
33,871 POSTS

Take it back to the shop that did the work. The last step of any repair is to verify proper operation. How can they justify handing you a bill when the problem wasn't fixed?

Running the battery dead does not ruin it. It simply needs to be recharged, but if it is nearing the end of its life, it can be permanently damaged by charging it at a high rate. Alternators put out a fairly smooth DC current. Battery chargers put out a pulsing DC voltage that drops to zero volts and goes up to around 18 volts 120 times per second and causes a corresponding pulsing current flow. That causes the plates in the battery to vibrate. Battery manufacturers know the lead is going to flake off the plates and how long it will take, and set their warranty periods accordingly. That's why batteries usually fail shortly after the warranty ends. High rate charging that vibrates the plates helps the lead flake off faster and it builds up in the bottom of the case. When that lead builds up high enough, it shorts that cell. Charging at the slowest rate for a longer period of time, typically half an hour, reduces the chances of battery damage.

The alternator is only one part of the charging system. The voltage regulator lives inside the Engine Computer, and the wiring between the alternator and computer must be checked. Before your mechanic condemned the alternator, he should have measured the voltages on the two small wires on the back. You can do that too with a cheap digital voltmeter if you can get to those wires. One must have full battery voltage when the engine is running. It will have 0 volts when the engine is not rotating. The other wire will have a lower voltage, but it must not be 0 volts. 4 - 11 volts is typical. The large bolted-on wire must have full battery voltage all the time. Those three voltages will tell where to go next.

Caradiodoc

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Friday, April 23rd, 2010 AT 6:42 PM