Every day, technicians from across the country post questions and get helpful answers on ALLDATA Community. Due to the sheer volume of data being entered, recognizable patterns and trends quickly begin to develop. The following Tech Tips have been created from some of the most popular real-world cases that have been solved on Community. If we’ve seen these issues occur numerous times with these particular vehicles, there is a good chance you’ll see them show up in your shop. For more valuable Tech Tips, visit http://www.alldata.com/tech-tips.
Envoy Stalls When Using Left Turn Signal
Vehicle: 2002 GMC Envoy, 4WD, L6-4.2L, VIN S, Automatic Transmission/Transaxle
Mileage: 136,004
Problem: The vehicle stalled only when activating the left turn signal. The customer also noticed that the left headlight was dim. The customer replaced the headlight but there was no change. The stalling problem began to get progressively worse until it happened constantly.
Details: The technician found only 2.0 volts on the ground circuit of the headlight and the left turn signal. Both components were grounded at the same location (G107), which is located on the engine block. Although the ground looked good and tight, the bolt was corroded and a little rusty. The wiring diagram showed that the fuel pump relay was also grounded at the location.
Confirmed Repair: The technician wire-brushed the contact point on the engine block and replaced the bolt and washer. The headlight was now bright and the stalling problem with the left turn signal was also resolved.
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Ram in “Limp” Mode - No power with DTCs P0335, P0642 & P2122
Vehicle: 2006 Dodge Ram 1500, 4WD, V8-5.7L, VIN 2, Automatic Transmission/Transaxle
Mileage 94,587
Problem: Vehicle had DTC faults: P0335 for crankshaft position sensor, P0642 for sensor reference voltage 1 circuit low and P2122 for APP sensor circuit. The engine also lacked power.
Details: The technician found a wiring diagram included with the P0642 DTC diagnosis chart. All three (3) codes could be set by the sensors residing on the same circuit. The technician tested the circuit to verify a 5-volt reference. The pink/yellow wire was only showing 1.6 volts at the PCM. The technician thought one of the sensors could be shorted so he disconnected all of them – the wire was still reading 1.6 volts. He then disconnected the pink/yellow wire from the PCM – now there was 5 volts coming out of the PCM. Using the wiring diagrams, he located the engine oil pressure sensor that was also powered-up on the same circuit. Once that sensor was disconnected, he finally got 5 volts back at the PCM.
Confirmed Repair: Once the engine oil pressure sensor was replaced, the technician cleared the codes and road tested until all the monitors were complete and the problem was corrected.
Grand Prix Lacking EGR Flow – DTC P0404
Vehicle: 2001 Pontiac Grand Prix, V6-3.8L, VIN K, Automatic Transmission/Transaxle
Mileage: 138,446
Problem: This vehicle came into the shop with DTC P0404, which set right away after clearing. The customer noticed the engine stumbled on mild acceleration.
Details: The EGR valve could be commanded open with a scan tool. The engine only stumbled at idle when commanded to 60 percent. The technician removed the EGR valve and inspected all ports. All ports were clear. Scan tool PID information showed that the EGR position voltage was only 1.75 volts when the valve was commanded to the wide-open position. The voltage at the sensor matched the scan tool data.
Confirmed Repair: The technician replaced the EGR valve. Now the position voltage reached 4.25v at the wide-open position. The DTC was cleared and the vehicle test driven. The problem was resolved.
