Quick summaries help with vexing mechanical issues

By ALLDATA Tech-Assist Team

Here’s a compilation of some of the “Tech Tips” ALLDATA compiles as its Tech-Assist Team helps technicians tackle vehicle issues. More detail on these tips — including marked-up schematics, images and recommendations — are searchable in the “ALLDATA Community” (https://www.alldata.com/alldata-community).

2004 Mercedes No Crank Issue

Problem: The engine on a 2004 Mercedes Benz SL 500 (230.475), V8-5.0L (113.963), with automatic transmission and mileage of 198,009, failed to crank over when the ignition was switched to the START position.

Details: The first thing the technician did was to connect a scan tool. He retrieved a B1829 (Starter battery circuit component error) diagnostic trouble code (DTC). Next, he pulled the starter relay out of the fuse box and measured voltage between relay socket terminals 85 and 86 (control coil) while the ignition was in the crank position. There was battery voltage at terminals 85 and 86, and on terminal 30. He connected a fused jumper wire to bridge terminal 30 to terminal 87. The starter engaged so he deduced that the relay was faulty.

Confirmed repair: The technician replaced the starter relay and cleared the DTC. The new relay restored normal cranking, the engine started, and no code returned.

A/C intermittently shuts off on 2007 Rav4

Problem: A 2007 Rav4 4WD, V6-3.5L (2GR-FE), with automatic transaxle and mileage of 190,668, was brought to the shop because the A/C compressor would shut off intermittently, and when it did, the A/C button light flashed.

Details: The technician connected a scan tool and pulled the following diagnostic trouble codes:

• B1422- Compressor Lock Sensor Circuit

• B1421- Solar Sensor Circuit (Passenger Side)

• B1424- Solar Sensor Circuit (Driver Side)

The technician called Tech-Assist for a strategy to diagnose the problem. After looking at the A/C system wiring diagram, the Tech-Assist consultant recommended first checking the resistance of the compressor lock sensor, which is located on the compressor (Connector B47). The resistance between SSR+ (pin 1 – Lt GRN) and SSR- (pin 2 – WHT/BLK) should be between 65-125 ohms. (See image 1) If the sensor resistance is out of specifications, the compressor needs to be replaced.

Confirmed repair: The technician measured 250 ohms on the compressor lock sensor pins. He installed a new compressor and cleared the DTCs. The A/C system was returned to normal operation and the two solar sensor circuit DTCs did not return. Fixed!

Delayed engine shut down (2013 Nissan Versa)

Problem: The 2013 Nissan Versa Sedan, L4-1.6L (HR16DE), with CVT transmission and mileage of 68,452 came in to the shop because the engine would continue to run four to five seconds after pressing the Start/Stop button; it used to shut off right away.

Details: The Tech-Assist consultant advised the technician to monitor voltage on ignition-related fuses with the ignition off to see if there was any feedback voltage from a component. The technician found many ignition fuses in the Intelligent Power Distribution Module (IDPM) remained at 6-7 volts for a few seconds after the Stop button was pushed. Next, he was advised to pull fuses one at a time until the voltage dropped to 0-volts at the exact moment the Stop button was pushed.

Feedback voltage was coming through fuse #54 in the IPDM. It was feeding voltage to other fuses on the same circuit. (See image 2) The tech traced the circuit on fuse #54 to find that it went through the E21/B12 connector in the driver’s footwell. He found that the connector was very corroded, and the pins were shorting together. (See image 3)

Confirmed repair: The tech replaced the pins and both connectors and that resolved the problem.

Power windows inoperative on 2007 Expedition

Problem: A 2007 Ford Expedition, 4WD, V8-5.4L, with automatic transmission and mileage of 188,998 was brought to the shop because the power windows were inoperative. They were all down about 2” and would not go up or down. The customers stated that they could hear a buzzing from the master switch.

Details: The shop replaced the master switch with an OEM part, but the symptoms remained. The Tech-Assist consultant suggested testing the main power wire. The test lamp would barely light. Carefully using a power probe to apply power to that pin, the windows would operate. It was apparent that there was a voltage drop somewhere.

The Tech-Assist consultant and technician traced the circuits together in a wiring diagram from ALLDATA Repair. The technician began tracing the harness and found a wire partially broken under driver’s door sill plate. It had only a few strands left which allowed minimal voltage through the circuit.

Confirmed repair: The technician repaired the wire and windows worked again.

2003 Camry with A/C problems

Problem: A customer brought a 2003 Toyota Camry Sedan, V6-3.0L (1MZ-FE), with automatic transmission and mileage of 199,996 to the shop because the climate-controlled air conditioning (A/C) wasn’t working.

Details: The shop determined that the A/C compressor was bad and replaced it. After replacing the compressor, the A/C system had another issue. The green A/C light would begin flashing soon after activating the A/C system. The technician connected a scan tool and found that the ECU was recognizing a request to engage the compressor clutch, but the clutch never engaged. At this point, the technician called Tech-Assist for advice.

The Tech-Assist consultant remembered a similar case he had worked a short time ago. He advised the technician that it’s common for the A/C relay in those vehicles to cause the same symptoms. 

Confirmed repair: The technician replaced the A/C relay and the compressor began working as designed.

2011 Ford E-350 cranks but won’t start

Problem: A 2011 Ford E-350, V8-5.4L, with automatic transmission and mileage of 86,002 was towed into the shop because the engine would crank over but not start. There were no diagnostic trouble codes (DTCs).

Details: On the initial call, the technician related that he had already applied battery power to the fuel pump and it ran. He also noted that there appeared to be a voltage drop in the wires between the fuel pump and the fuel pump module.

The Tech-Assist consultant suggested load testing the power and ground circuits. While load testing the ground circuit to fuel pump, the technician noted that the voltage was dropping out. He also checked the ground circuit to fuel pump module. It was also dropping out.

Together the two worked to identify the exact locations of all the fuel-pump related circuit grounds in ALLDATA Repair. Armed with that information, the technician traced the ground circuits and found a broken chassis ground strap (under the passenger seat).

Confirmed repair: The technician replaced ground strap and the fuel pump operated normally. The engine started and ran perfectly.  •