QuestionQUESTION: Good morning. I have a 1993 Chrysler Concorde with a 3.3 liter. It was idling one day for approx 2 minutes in 10 degree weather when it just shut off like you turned the key off. I noticed no fuel pressure on the fuel rail so I checked the fuel pump, no power. I picked up a snap on scanner and it displayed, no communication to module. I bought new relay's (fuel pump and auto shut down) and checked the fuses inside the car. I bought another computer from ebay which I installed last night, no luck. Normally, I can here the fuel pump turn on, seems to be still shut down. My computer is a 5427, can these be tested out of the car?
ANSWER: Hi Scott,
I may have misinterpreted when you said you checked the fuses "inside" the car. How about fuse A (20 Amp), the rear-most fuse in the inboard row of 5 fuses in the power distribution box under the hood? That is the supply fuse for the fuel pump relay and pump. Check to be sure you have 12v at the front pin of the relay socket.
The computer should normally close that relay for about a second as you noted, so have a friend turn the key to the run position while you listen/feel whether that really is closing monentarily.
Also, why not try the on-board diagnostic capability? Using the ignition switch:"on-off-on-off-on and leave on" doing that in 5 seconds or less elapsed time. Then watch the check engine light, which remains 'on', to begin to flash, puase, flash, etc. Count the number of flashes before each pause, then repeat the process to verify the set of counts. Then group the counts in pairs to form the 2-digit fault codes. Then write back and tell me those codes or you can go to www.allpar.con/fix/codes.html for a translation. We can go from there to find a solution. I don't know of a 'test' for the computer, but a code of 62,63, or 66 indicates a problem with the digital system in one way or another. The 55 code simply means 'end of readout' and it will always be the last number to come out.
Roland
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---------- FOLLOW-UP ----------
QUESTION: Hi Roland,
I did find that the 20amp engine controller fuse blown, looked good but measured bad. I robbed another 20amp from interior lamps, blew this one too when trying it. Also, I tried the on-board diagnostics, no response with pulsing engine light. I am stopping for more fuses today. I'll try again after work. Any more idea's that would take out the engine controller fuse?
Thanks
Scott
AnswerI am not certain what you mean by the "engine controller fuse". If you mean fuse A then that one is assigned only to the fuel pump relay which when it closes sends the current to the fuel pump. Were that the case, try removing the relay and see if the fuse still blows. If not, then try disconnecting the power at the fuel pump plug, after re-inserting the relay, and see if the fuse blows. If so, then you have a short in the wire from the relay to the fuel pump, if not then the fuel pump motor is shorting ground. You can access the fuel pump via a plate located in the floor under the rear seat. It has an 8-pin disconnect that carries the current from the relay on the dark green/black wire.
If you mean fuse B then that one's current goes to power the pcm (engine controller)/tcm (transmission controller)/transmission control relay in the power box/transmission solenoid box on the transmission. So any of those circuits/devices could cause that fuse to blow. You could disconnect each and see which one, when disconnected prevents the blowing of the fuse.
Roland
PS: Thanks very much for the nomination. By the rules of the site, you are entitled to click on "yes" again to give me another nomination to be volunteer of the month, based upon this answer. Thank you for giving me a second consideration.
