jonnydclar

Hello,
I'm in need of some advice. First a quick history. I'm a shade tree mechanic / with an engineering degree.

1999 GS300 just bought with ABS/VSC lights on. Mechanic said he could not troubleshoot because I needed an alternator... one diode out. Everything had been running fine so I was skeptical but when I checked voltage at idle it was 12 V and high rpm 13 V. It took 3 days for the alternator to come in and I drove it for ~ a day and experienced this stuff in this order but not all on the same trip.
low idle... like 300 rpm and rough
limp mode just out of the blue
huge swings in fuel, transmission shifts, CEL P1121

I installed a new Bosch alternator and now have 14 V at idle. Disconnected the battery for the 40 minute job which should have reset everything. No change in behavior.

I ohmed out everything using the procedure found on page 2 of this link

http://bahamutcars.free.fr/workshop/...nts/index.html

which is a great resource by the way. Everything checks ok according to the resistances given. With the key on and slowly moving the throttle cable I hear corresponding movement in the motor.

Could the bad alternator kill my computer?

Is the transmission shifts indicative of the pedal position sensor being bad? Is the low idle (just that one time not happening now) cause the throttle control motor to be suspect? I tried checking the TPS for resistance changes as I turned it but did not see anything which made it look suspect.

Any insight would be appreciated.

GS4_Fiend

iTrader: (22)

Do a load test on the battery see how it does. According to the history of this problem on the forum, the results were: bad charging system (battery can't handle the load), clean MAF sensor, aftermarket intake, bad idle valve motor, bad tps. All of these would lead to rough idle and/or driveability problem. Do a search on "rough idle" and "clean maf sensor". Hope that helps.

jonnydclar

... and I'm pretty sure the low idle is unrelated. It only happened once and it was before I replaced the alternator. It may have been lugging the battery at the stop light. Everything on the car is stock except stereo / alarm stuff. I'll check the battery.

frankjames

Pull ur codes. go to autozone or do it urself. that will point you in the right direction. also refer to the million other threads under the 2gs on the same issue. Mine was throttle control motor, resistance not in spec even though reading. see if you pull P0120 or P0121 to start.