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Motor, Jul 2007 by Rosario, Tom
Start your repair by replacing or repairing affected connectors, splices, switches, components, etc. Grab some wiring schematics and let the symptoms be your guide to exactly which circuits require your attention. Once all the electrical issues have been sorted out, look for a pinched wiring harness in the area where the evaporator housing meets the cowl. The harness may be preventing the evaporator drain hose from seating properly in the hole in the body where condensate escapes. If you see a harness in the area, relocate it away from the evaporator drain. Finally, check for and remove excess sealer in die area of the evaporator drain and body hole.
GM Truck
Brake warning lamps illuminated. Some 2003-05 Chevy Silverado and GMC Sierra 2500- and 3500-series HD trucks may illuminate both the ABS and Service Brake System warning lamps on the dash. The problem typically occurs on initial start-up, is usually intermittent in nature, is more likely to surface on trucks with a diesel engine (though it can occur with gas engines, as well) and won't store a hard DTC in computer memory.
A timing issue related to the cranking/starting regimen is the likely cause of the bogus warning lamps, says GM. Reprogramming the Electronic Brake Control Module with updated software should eliminate the annoyance immediately. You'll find the updated files in TIS software version 7.5 or later.
Honda
MIL on, evap DTC stored. The owner of a 2007 Fit model may come into your shop one day alarmed that the MIL is on. If he does, hook up your scanner and start poking around for DTCs. If the only code you come across is P0451 (fuel tank pressure sensor range/performance problem) and the car was built between VINs JHMGD3...7S000001 and JHMGD3 ...7S017916, the PCM may simply be misinterpreting the pressure sensors input signal, says Honda.
To make a definitive diagnosis, take a look at the VSS parameter in the freeze frame data. If the code set at greater than 5 mph, continue with normal troubleshooting. If the code stored at under 5 mph, the pressure sensor's signal is being skewed by the engine management system. Reprogramming the PCM using HDS software version 2.005.008 or later should wipe out the code and turn off the MIL immediately. Here are the specifics on the software:
PGM-FI Program ID PGM-FI Program Part No.
MEA140 or later ... .37805-RME-A14
MEA659 or later ... .37805-RME-A65
MEA850 or later ... .37805-RME-A85
Ford
MIL illuminated, lean exhaust DTCs stored. Some 1996-98 Ford Contours and Mercury Mystiques with the 2.OL 4-cylinder engine may turn on the MIL and log lean exhaust codes P0171 and/or P0172 in PCM memory. One possible cause for the illuminated MIL and lean codes, notes Ford, is a contaminated mass airflow sensor. A revised, better-quality MAF sensor (Part No. F5RZ12B579-B) is now available to address the concern.
To determine if the new sensor will do any good, hook up your scanner and start hunting for codes. If DTCs other than those above are stored, take care of them first. After that, or if the only code you pull is the P0171 and/or P0172, start your diagnosis by checking the air induction system for leaks or obstructions. If everything looks good, start the engine and allow it to reach normal operating temperature. With all accessories off and the transmission in Park or Neutral, note the barometric pressure reading on the scanner display. It should be within ±8Hz of the normal reading for your altitude. Next, look at the output voltage from the MAF sensor. It should be no greater than .70 volt. Finally, take a peek at the PID for long-term fuel trim. The reading shouldn't exceed -12%. If any two of the three specs are out of range, install the new, revised MAF sensor with confidence. If most or all are within bounds, grab a repair manual and follow Pinpoint Test H for either of the two lean DTCs.
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