Low Speed Fuel Pump Primary Circuit Malfunction The PCM monitors the low speed fuel pump (LFP) primary circuit output from the PCM.
The test fails if: When the LFP circuit is commanded on (grounded), excessive current draw is detected on the LFP circuit; or when the LFP circuit is commanded off, voltage is not detected on the LFP circuit (the PCM expects to detect VPWR voltage coming through the low speed fuel pump relay coil to the LFP circuit). Open or shorted low fuel pump (LFP) circuit Open VPWR to low speed fuel pump relay Damaged low speed fuel pump relay Damaged PCM An open circuit or short to ground can only be detected with the low speed fuel pump.
In most cases, the TCM is integrated into a single housing with the PCM. Nevertheless, the section of the module which controls (automatic) transmission function may be powered up separately. In any case, the TCM is typically powered using switched (only present with the ignition switch in the ON, start, or run position) voltage. This circuit is normally equipped with a fuse, fusible link, and/or a relay. Frequently, the PCM and TCM are powered using the same relay albeit by separate circuits. Access to a reliable vehicle information source will yield necessary details of the TCM power circuit for the specific vehicle in question.
Difficulty Level (Soso)
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Repair Time (30 Min.)
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| Cost Prediction : $ 80-120 |
If your transmission mechanical 4-wheel drive axle lock lamp circuit short to battery check engine light is illuminated, it's best to take it in for diagnostic testing, which can feel like a hassle. Because while the lights vary in appearance from vehicle to vehicle, all have the same basic meaning: There's a problem with the car's emissions system. The on-board diagnostics system U3909 and engine control unit are in charge of monitoring a bunch of different transmission mechanical 4-wheel drive axle lock lamp circuit short to battery, and if they get a reading that's a little out of whack, up pops the check engine light.
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U3909 is a kind of Network Trouble Code
U-code indicates that engine communication errors and shows lost communication with engine parts.U-Codes are fairly straight forward, given all of the articles and technical publications that have been written regarding these problematic codes. In most cases, it just comes down to identifying the module that isn't communicating with the other modules on the CAN bus line for whatever reason. |
You can view according U3909 DTC for your car model. We selected several models to see obd2 solutions click and view it.
| +U3909 Genesis G80 | +U3909 Pontiac Piranha | +U3909 Bertone Birusa | +U3909 Mercer 35 | +U3909 Dellow Mk |
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