egr and instrument warng lights

1987 TOYOTA PICKUP
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GAST9406
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I accidently shorted the batter to ground for about 30 seconds. Blew voltage reg. and 40 amp fuse, which I replaced. New Battery. Now "Charge" and "Brake" warning lights are off at low rpm but go from very dim to bright as rpm increases and dimmer as rpm's decrease.
I also have a new Emissions control problem. The engine runs very rough above idle at steady rpm but it runs good on sudden accelleration.

I have a three port EGR modulater and using the" ALLDATAdiy.com" site info, I stumbled across the fact that if I disconnect the vacuum line to the single port side, the engine smooths out and runs great at all speeds but the lights are the same. I assume the modulator is opening the EGR valve when it should be closed. Is there a common electrical component that would cause both these problems or do I have seperate issues here?
Jul 18, 2008 at 11:24 PM
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MERLIN2021
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Have you tested the alternator itself? May have a bad diode now...if the voltage is too low, sensors and computer may not be operating correctly.
Jul 19, 2008 at 6:53 AM
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GAST9406
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I had the alt checked while I had it out and the only indication was that thr reg was bad. I also checked the voltage at the ign and eng fuses aqnd it was 11.98 volts. Is that too low? It seems that if it was too low that the opposit would be true, that the indicator lights would be brighter at low rpms and dimmer at higher rpm's. Could it have something to do with the Amps too high? Does the regulator control the amps as well as the voltage? Is there a connection to the EGR problem?
Jul 19, 2008 at 7:54 AM
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MERLIN2021
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Hook up a voltmeter and start the truck, readings at the battery should be 13.8-14.8 volts, any lower than that and there is a charging problem, can be a battery or cables, alternator/regulator, fusible link can be blown, especailly if the jumpers were hooked up wrong...

ON-VEHICLE Preliminary Inspection Check alternator wire harness connections and drive belt tension. Check "ENGINE", "CHARGE", "IGN" and alternator fusible link for continuity. Battery must be fully charged prior to beginning test. No Load Test

1. Connect battery/alternator tester according to manufacturer's instructions. Check amperage and voltage with engine running at 2000 RPM. On all models, alternator output should be less than 10 amps.

2. Voltage should be 13.0-14.8 volts on Corolla and Tercel (without IC regulator). Voltage reading on all other models should be 13.5-15.1 volts.

3. If voltage reading is above specified range, replace IC regulator. If voltage reading is less than specified, ground "F" (full field) terminal. See Fig. 2 .

4. If voltage now climbs above specified range, replace IC regulator. If reading remains below specified range, repair or replace alternator. Turn on high beam headlights and place heater control on "HI". Run engine at 2000 RPM and check amperage. Ammeter should read more than 30 amps. If reading is less, repair or replace alternator.

If reading is low due to a fully charged battery, it may be necessary to crank engine with coil disconnected for about 15 seconds to partially discharge battery.
Jul 19, 2008 at 10:34 AM