Lots of help here. You need a good auto-electrician with a pro grade scan tool. There are soooo many modules in that vehicle and I have a vague recollection there is a box of tricks under the seat!.
https://www.google.com/search?q=2002+yukon+won%27t+start
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Is there B+ voltage on the heavy gage wire on the back of the alternator ? Possible blown fusible link. Plus the two wires in the connector go to the PCM - engine computer . One is the turn on signal ,the other is charge indicator control . Having the vehicle checked for DTC'S - diagnostic trouble codes should also be done .DTC P1637
The powertrain control module (PCM) uses the generator turn on signal circuit to control the generator. A high side driver within the PCM allows the PCM to turn the generator ON and OFF. When Generator operation is desired, the PCM sends a 10 volt signal to the voltage regulator via the generator turn on signal circuit. This causes the voltage regulator to begin controlling the generator field circuit. Once the Generator is enabled by the PCM, the voltage regulator controls generator output independently of the PCM. Under certain operating conditions, the PCM can turn Off the generator by turning Off the 10 volt signal on the generator turn on signal circuit. The PCM has fault detection circuitry which monitors the state of the generator turn on signal circuit. If the fault detection circuit senses a voltage other than what is expected, this DTC will set. The voltage regulator also contains fault detection circuitry. If the regulator detects a problem, the regulator will ground the generator turn on signal circuit, pulling the voltage low. This also causes the PCM to set the DTC.
Your best bet mite be to take it to a qualified repair shop.
At www.reliable-store.com get complete guide on whether to repair or not, service it, and how to repair etc, along with wiring diagrams, electrical diagrams, torque specs, error codes, everything.
Ok you might need to open and close your key switch about ten times before trying to start it. Off position the on position, not start but on then off. Ten time.
It sounds like a wheel bearing is going bad. They are easy to change. If you have a place to jack the vehicle up. Try spinning the front wheels. You should hear a scraping noise as the wheel turns.Also replace both sides at the same time,as the otherside is not far behind.
When the check engine light comes on a fault has occurred and a fault code or codes is recorded in the Powertrain control modules memory. What you need to do now is have the fault code or codes read and then perform diagnostics based on what the codes are.
Could be the custer is the problem , do you know how the gauges get their info. Do you know what class 2 serial data communications are . The culster is shorting out the data network or possibly the VSS - vehicle speed sensor . or input speed sensor . These sensors are powered by the five volt reference circuit from the PCM . Sensor's go bad internally with heat , after warm up . an bring down the network . Testing the five volt ref. circuit ,is the way to diagnose .
Speedometer
The IPC displays the vehicle speed based on the vehicle speed signal from the PCM. The PCM converts the data from the vehicle speed sensor to a 4000 pulses/mile signal. The IPC uses the vehicle speed signal circuit from the PCM in order to calculate the vehicle speed. The speedometer defaults to 0 km/h (0 mph) if a malfunction in the vehicle speed signal circuit exists.
Engine Coolant Temperature Gage
The IPC displays the engine coolant temperature as determined by the PCM. The IPC receives a class 2 message from the PCM indicating the engine coolant temperature. The engine coolant temperature gage defaults to 75°C (160°F) or below when:
• The PCM detects a malfunction in the engine coolant temperature sensor circuit.
• The IPC detects a loss of class 2 communication with the PCM.
How to check the 5v reference circuit for short to ground Cadillac
Take it to your local parts store. Most will check the codes for you for free. Once you have the codes, you can look them up and see what's likely wrong.
Not the Onstar. You have an amp in it that needs rewired. Color code for wires are so different. I use an ohm meter to fix the problem. Just a note. Onstar does't work after this.
Is there hot coolant entering the vehicle??? Check heater hoses to make sure both are about the same temperature. If only one is warm/hot.... you have a restriction/plugged up heater core
