After replacing the water pump in my 2004 trailblazer it ran great. Then when my brother disconnected the negative terminal to the battery to reset the computer. When he hooked it back up it no longer idles when the ac is on it drops rpm and dies. What is wrong

Anti-theft has nothing to do with it ,disconnecting the battery won't do anything either . You left something disconnected or by not disconnecting the battery you blew a main fuse somewhere some how. You had to take a few things apart to get at the water pump. You need to find battery power distribution wiring diagrams an check with a voltmeter. See it all the time ,rookies

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Chevy Trailblazer 2002 2009 Factory Service Workshop repair manual

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(this damages the ecu Disconnected negative terminal and car still ran) check and clean the alternator connections. and check the earths. light can come on if water has gotten into the alternator or the connection has come loose. you don't disconnect the battery when the engine is running as it can shock the ecu alternators have a built in voltage stabilizer but this only works with feed back from the battery no feed back it can convert ac instead of dc and blow up the ecu. it also damage other parts.

Did she disconnect the negative terminal from the battery when replacing the fuse? Is it possible she swapped fuses instead of replacing them? One easy thing to try is to disconnect the battery for at least 30 min to allow the PCM (computer) to reset itself.

The general recommendation is to put the negative on first, but on your Trailblazer it doesn't matter.

is it turning over,have you checked the starter?if so spray some brake cleaner in the throttle body and see if it will start.









TIM............

It could go off after running some unleaded gas such as a couple gallons of 'premium unleaded' through it. But you should also try to reset it. To do this follow these simple steps:

1. Write down the radio code of the car.
2. Disconnect the battery negative terminal for about twenty minutes. Then reconnect back the battery negative terminal.
3. The indicator light should be 'off'.

Disconnect the battery negative cable for ten seconds but make sure you get the car radio code before you do this.

2004 Jeep Liberty 4WD 3.7L MFI SOHC 6cyl
Starteer - Removal & Installation

2.4L & 3.7L Engines

1. Before servicing the vehicle, refer to the precautions in the beginning of this section.
2. Disconnect the negative battery cable.
3. Remove the starter mounting bolts.
4. On the 3.7L engine, the left side exhaust pipe and front driveshaft must be disconnected.
5. Disconnect the starter solenoid harness connections.
6. Remove the starter.

To install:



Fig. Starter mounting: 2.4L engine



Fig. The starter position for the 3.7L engine

1. Connect the starter solenoid wiring connectors.
2. Install the starter and torque the bolts to 40 ft. lbs. (54 Nm).
3. On the 3.7L, the left side exhaust pipe and front driveshaft.
4. Install the negative battery cable and check for proper operation.

2.8L Engine

1. Disconnect and isolate negative battery cable.
2. Raise and support vehicle.
3. Disconnect solenoid wire connector from solenoid terminal
4. Remove battery cable from stud on starter solenoid.
5. Remove 3 starter mounting bolts.
6. Remove starter from transmission bellhousing.

To install:

1. Position starter motor to transmission housing.
2. Connect battery cable solenoid terminal wire harness connector to connector receptacle on starter solenoid. Always support starter motor during this process. Do not let starter motor hang from wire harness.
3. Install battery cable eyelet terminal onto solenoid B(+) terminal stud.
4. Install nut securing battery cable eyelet terminal to starter solenoid B(+) terminal stud.
5. Refer to torque specifications.
6. Position starter motor and install 3 bolts. Tighten 3 bolts in this sequence: top bolt, bottom bolt, middle bolt. Refer to torque specifications.
7. Lower vehicle.
8. Connect negative battery cable.

Also can review the Service Repair Manual for Jeep KJ Liberty

I really hope help you with this (remember rated this help) Good luck.

try changing the air filter ,i had a problem ,at ilde in drive my trailblazer would stall, changed the air filter now it's not stalling and got my power back ,there is a secondary air pump that i have to change ,
not sure were it is ? still not running perfect but it's running better .and my service light is on too.
i got it put on scope ,it's the pump .
not sure if this helps ,but i'm start to run in to problems too,i have a 2004 trailblazer.
i like to do fix things myself ,i hope i can.it's the cost if you know what i mean.