Hope someone may be able to help.
Have a 87EMS Saab and the car has a problem when i turn on the full lights. Its draining the engine power to a point where it can conk out in first gear. Checked out the battery and the altermeter and even got the local garage guy to check them out and all fine.
Is it an electric problem. Can't figure it out and can't see what it could be besides the above.
Any help before i bring it to a specialist................
Most likely the alternator, but could also be that you have a marginal ignition system (e.g. coil).
Check the voltage across the battery with the engine running. Should be min 13V. Now turn on your lights + rear window heater. Check voltage again. It will have dropped, but should be min. 12V.
As far as DIY, confirm that voltage at batt virtually matches that at alt, with engine running
Ck that all grounds are clean & secure, including alt ground, batt neg, and chassis grounds
A couple of special/expensive tools (shop should have) will measure the alt's _amperage_ output. Less likely is a problem w/AC ripple current (can be done with a multimeter and better yet w/a scope). And hopefully both batt and alt were load tested
Does this prob only happen w/lights or does it happen with other 20A -
30A circuits (interior blower fan, when cooling fans kick on, etc)?Lance
I don't know anything about the 87EMS specifically, but I had three 900S models from the early 90's. All three had a problem similar to what you describe - they simply wouldn't keep the battery reliably charged. The battery was always right on the verge of complete discharge. As a result, sometimes they simply wouldn't crank after sitting in the garage for a couple days. Sometimes they would simply die as I was driving them. Sometimes they would die after idling for 5 minutes. Running the radio with the ignition off was a no-no. In every case, the battery was completely discharged, and a battery charge would bring it right back. I took each one to a Saab garage, and was assured each time that everything was OK (but they sold me a few batteries just to be sure).
The solution turned out to be simple and cheap. In my 900's, the electrical path from the alternator to the battery is long, contorted, and subject to all sorts of bad connections and corrosion problems. I simply bought two 10-foot lengths of number 10 wire (one red and one black), crimped and soldered ring lugs to the four ends, and ran direct connections from the alternator, across the top rear of the engine, to the battery. In the last five years, the discharged-battery problem has not returned even once.
Couldn't hurt to try ...
Bill Jeffrey =========================
Ed wrote:
Thanks for your help.
Finally got the problem fixed. The car was leaking some petrol so the full power of the engine was never realised. This had an effect of not charging the alternator correctly so with the lights on it was working of the engine which was not full power. This also explained why the car was hard to start after leaving it overnight. (This I heard from my mechanic just now but gotta see if the blasted thing is fixed........no more having to warm up the car at night before i drive it)
Next i will have to tackle the dashboard lights :)
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