FAQs—GMC C1500 Suburban
My GMC C1500 Suburban is not starting and there's no spark at all. How do I fix this?
If your GMC C1500 Suburban cranks but will not start and has no spark, it could be because of one of several components. Check for voltage at the coil positive terminal while the ignition key is on. If there is voltage, then the problem could be on the trigger side of the coil, such as the crank sensor, ignition module, or primary wiring circuit. It could also be due to a bad high voltage output wire from the coil to the distributor, cracks in the coil output tower, or cracks or carbon tracks inside the distributor cap or on the rotor. However, if there is no voltage at the coil, then the fault may be on the supply side, which includes the ignition switch or ignition wiring circuit. Also, if you have a scan tool, you could plug it into your SUV's diagnostic connector and look for an rpm signal while cranking the engine. If there's no signal, then the problem could be a bad distributor pickup, a stripped distributor drive gear, a bad crankshaft position sensor, or a wiring fault.
While driving my GMC C1500 Suburban, the light switch on the dashboard gets extremely hot and the headlights shut down. What could be causing this?
First, replace the headlight bulbs. If they still shut down while you are driving your SUV, check fuse box for any discolored or burnt fuse and replace as needed. If this doesn't work, verify that power is coming through the wiring harness, and replace it if there's no power. Lastly, if the lights still shut down, inspect the headlight switch and see if it's discolored, and clean it with a pencil eraser until the discoloration is gone. If they still do not work, you might need to replace the headlight switch. You might need to have someone look at the switch, as you may need to touch the wires, which can be dangerous if you have no experience in electrical repairs. It is also best if you do some resistance checks of the circuits since this may help pinpoint the problem component.
I have a hard time accelerating over 30mph when driving my GMC C1500 Suburban. What can I do to fix this?
This usually happens when your SUV's engine misfires, stumbles, or lacks power when you accelerate or step on the throttle. This usually occurs because the air/fuel mixture is not being properly enriched or is going lean, or the ignition system is weak. To diagnose this problem, you will need a scan tool for any fault codes, as you will be using it to check sensor response by looking at the various sensor values. If ever the values are out of range or if the sensor is not responding normally, then you will need to test them using a DVOM. Aside from this, it is also helpful to search for vacuum leaks, inspect or clean the EGR valve, and measure the fuel pressure and volume.