Jeep grand cherokee v6 4.0 cranks but wont start has low voltage to all my senors
If you have verified low voltage using a scanner, keep in mind that some scanners will not differentiate no voltage from low voltage. Before testing, make sure the battery is fully charged and that all ground points are clean and secure. (in addition to the main battery cable to the block and fender, there are usually up to five more smaller wires on block and near the computer). Check all your fuses, especially those in the power distribution center.
To test further than that, you will need a good wiring diagram (chilton and haynes have diagrams but chilton seems to be more "readable" and accurate). First, follow test instructions in the manual and check each sensor. Then, use your multi-meter to check power at the computer harness plug, then follow the diagram and test wiring from the computer to the sensors, by disconnecting battery and using the ohm meter setting, checking for continuity from the computer harness plug to each sensor. (if you have a security system, find out how to re-set it before doing that) (Most commonly failed sensor is the crank sensor, followed by the cam sensor, so check both first) Most wiring problems happen at the connector ends either from a pin corroding (pin looks black) or where the wire joins to the pin.
Therefore, unless you see that a harness has burned or chafed through, normally you do not have to cut into taped areas. When working on a harness, it is often a good idea to use a notebook and write down the results, pin location and destination of each wire you check. That way, if an "odd" reading begins to show up in a shared wire, you can reference it to the diagram and get some idea of what is going on.
As you can see this is a bit complex....therefore I cannot give you a simple answer. If there, I'd need to do much the same as outlined above
In testing, you will invest some time, but will not be randomly replacing parts, hoping the problem will go away.
Jul 27, 2010 |
1998 Jeep Grand Cherokee