Acura repair proves to be challenging

Jan 26, 2024

The most difficult problems to diagnose are the intermittent ones. Last fall, we had a customer bring in his 2009 Acura TSX 2.4-liter.

The customer explained that if the engine warmed up and then was turned off for 20 minutes, it would have difficultly starting (long crank). He added that when the car finally restarted, the check-power-steering light would go on, the steering was hard to turn and the check-engine light went on. The customer also told us that he had replaced the starter and the crankshaft position (CKP) sensor in hopes that would repair the car.

After test-driving the car, we were able to reproduce the problems two different times. We then connected the diagnostic scanner and pulled code 22-01 (engine speed signal in the power-steering module) and code P0339 (CKP sensor, circuit intermittent in engine control).

We addressed the power-steering code first, as the customer had already replaced the CKP sensor. While we performed the test plan for code 22-01, we found that the power-steering system was not getting enough voltage. It is important to note that this car has one of the first electronic power-steering systems Acura used. We then tested the alternator output (14.1 volts) and the battery (10 volts at 250 amps for 15 seconds) – both were OK.

During the test, we found buildup on the positive battery terminal. We also found that multiple electrical systems were dropping voltage. We then performed a voltage-drop test on the starter and measured voltage between the battery and the engine control module (ECM). There was a 1-volt difference between the battery and the ECM. While we were performing the diagnostic, we found a service bulletin stating that if we have a voltage drop and a long crank, then we should replace the fuel pump relay, two ECM relays and ignition switch.

The ECM, fuel pump and starter are being supplied voltage from the ignition switch and main power relays. We suggested that the ignition switch, fuel pump relay and ECM relays be replaced and the positive battery cable cleaned.

Once those repairs were performed, we did not have any more troubles with the power steering, yet there was still a longer than normal crank intermittently and the check-engine light was on.

We again pulled code P0339. We performed a visual inspection of the CKP sensor and found that a rodent had been in the engine bay. The rodent had moved the CKP wire harness but had not eaten it. So, to be clear, we did not find a problem with the CKP sensor.

The main reason we wanted to replace this sensor was because it was an aftermarket product. We have had to remove aftermarket electrical parts many times and replace them with the original equipment supplier part.

Once the sensor was replaced, we cleared the code and performed a CKP sensor relearn (adaptation). We had to perform the relearn three times before it registered on the computer. We then drove the car several times without any problems. The customer then picked up the car.

Two months and 119 miles later, however, the car was back. It had a check-engine light on and an intermittent long crank. Once again, we pulled code P0339. Up until this point, we had performed all of the test plans in the proper order. When we get to this point, we have to retrace our steps and double and triple check each component.

While checking the components we replaced, we also checked the engine coolant sensors and the oxygen sensors. Everything was good – except the engine coolant temp sensor (ECT) at the radiator read 0 degrees. Strangely, though, it did not trigger a diagnostic code.

That made us think the ECM may have a problem. Computer problems on this car are extremely rare, but if the ECM is the corrupted component, it will not set a code. After doing a little more research, we learned that there was an update for this ECM. We checked the software level and confirmed that we could perform the update. We then reprogrammed the ECM and replaced the ECT sensor at the radiator. We did a test-drive, and everything was good.

Throughout the test plan, the car never showed us a code for the ECT sensor. This problem was a combination of issues. The fuel pump relay, ECM relays and ignition switch caused a steering problem. The ECT and possibly the software caused the long crank. This car was definitely a challenge.

Matt Pataky owns Sunnyvale Foreign Car Service, 15 Pioneer Way, Mountain View. For more information, call (650) 960-6988, email [email protected] or visit sunnyvaleforeigncar.com.

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