QuestionQUESTION: Hello,
The above vehicle won't start, at first it was an intermittent problem of not starting, then the car died while driving, I put some fuel system cleaner in and waited ten minutes and it started, it ran fine for a few days, but then died again while driving, after cranking until I had a dead battery, and jumping the car it started one last time, now it won't start at all. I suspected fuel, so in checking the pump relay I realized the computer was not energizing the relay during key on or cranking, I measured right at the computer pin out (pin 74). I tried hard wiring the fuel pump which gave me fuel, but the car still wouldn't start. I am suspecting a computer, but is there anything else I should check before throwing in a new computer?
Thanks
ANSWER: Hi Aaron,
I would suggest that you may have a problem with either the cam or the crank sensor, rather than the computer. When these are failing they often do so by quitting when they heat up, then recover upon cooldown. You can get a fault code readout for free at most Autozone parts stores which will tell you if that is the case and if so, which sensor. The relay will not close unless both of the sensors are working. You can also get a readout for around $40 at an independent shop. You may get some indication too by using the ignition key and the check engine light. Turn the key "on-off-on-off-on and leave on" doing that in 5 seconds or less elapsed time. The check engine light remains on but may then begin to flash, pause, flash, etc. Count the number of flashes before each pause, then repeat to get an accurate count. Then group the counts in pairs in order of appearance to form two digit numbers which are the fault codes. 55 is always the last code, it means end of readout. An 11 code is the crank sensor, a 54 is a cam sensor (which in the the case of the 2.5L engine means a new distributor, unfortunately). This key technique may not work, but also watch to see if the odometer window might show any fault codes if the check engine light doesn't flash. If neither, then a readout with a code checker is necessary to tell you which sensor or other circuit is the problem. Write back with the numbers and we can go from there.
Roland
---------- FOLLOW-UP ----------
QUESTION: Three followup questions for you. I hooked up a scan tool to the car before trying to hard wire the fuel pump on, and no codes were read, should I still suspect a cam or crank sensor? What would the computer disable in addition to the fuel pump to prevent the vehicle from starting? I didn't see an ASD relay in the main power distribution box, does this vehicle not have one?, thanks you are great.
ANSWER: Hi Aaron,
There is a rear section of the power distribution center under the hood that is hidden by the air intake, a little below the level of the front part of the box. The front right is the ASD the front left is the starter motor relay. The rear relays are fan relays.
The computer will cut off the ASD relay if it doesn't get pulses from the shaft sensors. That cuts the power to the distributor/coil, the spark plugs, the fuel injectors, and the oxygen sensors. In your car the fuel pump relay is controlled directly by the computer as you recognized, but that too is shut down along with the ASD without those signals from the cam and crank sensors. It is possible that one of the sensors is bad without there being a fault code. The way to check would be to measure the voltage on the sensors: the orange/white should have 8V, then measure the voltage between the signal (cam=tan/yellow, crank=gray/black) and ground (black/light blue) wires of the two sensor while turning the engine by hand with a socket on the crankshaft pulley. It should vary between 0.3 and 5.0 volts a few times per revolution. The crank sensor wires are at the 6-pin plug of the distributor.
Please let me know what you learn.
Roland
---------- FOLLOW-UP ----------
QUESTION: Hi Roland,
I'm still struggling with this vehicle, The other day when working on it, i left the key in the on position, it was there for two or three days, when I came out to it the battery had .4 volts on it. So I hooked some jumper cables up to it, unfortunately I had not hooked the 6-pin wire harness back up to the distributor, so in cranking, it tripped the code 12 and 54 which appear to be a dead batt code and the no signal from cam position sensor. So after hooking the plug back up to the dist. I tried starting again, and guess what it started!! I ran it for about 5 minutes during which time the transmission acted funny (it has been acting up lately) anyways after turning it off, I tried starting again immediately, and it didn't start, so I tried measuring the 8v signal first at the dist plug on the orange/white wire, no voltage, then I probed the wire coming straight out of pin 44 on the computer, no voltage. Any Ideas? The 8v supply had to be working when the car turned on but why then did it quit after that? Sorry, to keep bothering you but I sure appreciate your help!!! maybe we'll get it this time.
AnswerHi Aaron,
The 8V is supplied from inside the PCM. The possible reasons for its disappearance are:
The orange/white wire from the PCM to the distributor is shorted to ground intermittently; possibly the cam sensor itself is shorted to ground. Check these possibilities with an ohmmmeter.
The 12V supply to the PCM is missing (dark blue/white at pin 20) should be there in the start and run positions of the ignition switch; comes from fuse 10 of the PDC.
The ground for the PCM is open (black/tan at pin 50) connects to the left strut tower on black/red wire.
Failure of the voltage supply source internal to the PCM.
Those are the possible causes that I know of.
Please let me know what you learn. Keep at it!
Roland
