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George H.
George H., Subaru Certified Technician
Category: Subaru
Satisfied Customers: 15355
Experience:  ASE Master Tech 15 + Years
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1993 Subaru Legacy: error codes..The check engine light..cooling fans

Customer Question

The Car is a 1993 Subaru Legacy. This is two part question, now I need to know to access the error codes ( I assume that this year has flash codes) and I would then need to know the meaning of the codes.
The check engine light is on, and the cooling fans are running constantly.
Submitted: 4 years ago.
Category: Subaru
Expert:  George H. replied 4 years ago.

Hello I will help you with your question,

 

There are a pair of green "DCheck" connectors under the dash on the drivers side. This is right hand drive? Connect them together and turn the key to run. The check engine light should blink a series of codes with a long blink followed by two short blinks being a "12"

 

Post the codes back here and I will help you determine the next action to take.

 

 

graphic

 

Customer: replied 4 years ago.
Hi George,
I plugged the two green test mode connectors together and turned the key to on, and no flash codes were generated, the check engine light just stayed on. Also regarding the cooling fans running continuously, they start as soon as the ignition switch is turned on and then plusate in time with some relays clicking behind the center console about every 3-5 seconds...something is screwed up. Any ideas on how to get those error codes to flash?
Chris
Expert:  George H. replied 4 years ago.

This is not a good thing and usually means that the computer has had it. Be sure that the pair of black connectors is not connected. They are near the green connectors.

 

If you confirm that the connectors are correct and that the powers and grounds for the computer are correct I would spend the diagnosis money to have someone with a select monitor check one last time before you bite the bullet and put a computer in ti. They are not inexpensive so it would be worth the money to be sure

 

Please let me know what I can do to help you with this

 

thank you

 

 

Customer: replied 4 years ago.
Hmmm, I just got home it is 715 pm west coast time, I did not connect any other wires under the dash other than the two green ones that you mentioned.
This all started happening about a week ago after we had a pretty low cold snap.
How do I check the power and grounds for the computer and where is it located?
There is a local u-pull-it yard that has a 92 that might have a computer in it. Would that work with my 93?
Thanks
Chris
Customer: replied 4 years ago.

George
I was considering the answer to my last post to be the second part of my question in diagnoising my problem, after which I would hit the accept button.
But it has been such a long time inbetween replies that the system says it is looking for other "experts" to answer..I am not sure how this works.
Chris
Expert:  George H. replied 4 years ago.

I was sleeping so I gues the system dosen't care if I get any rest!!

 

If you have a voltmeter check pins 2 and 13 in connector B48 for battery voltage and pins 11,22,21 in the same connector for ground. Check pin 14 in connector F47 for ground as well.

 

There is a small possibility that the ceheck engine light control wire is shorted to ground. This is found at pin #19 in connector F47

 

The connector views and location of the ECU are in the diagrams below

 

graphic

 

graphic

 

I don't have interchange information for the different years but you can check the numbers on the case to see if the part numbers match.

 

Do you have any issues other than the light being on? If not you can try resetting the system by removing the negative battery cable for an hour with the key in the run position then reconnect the cable. It may allow the computer to reset.

 

 

Customer: replied 4 years ago.
Thanks, XXXXX XXXXX check all those things and I will try resetting the computer and yes it does have other issues that started about the same time:
The cooling fans run constantanly and occassionally on there own will do what they are now doing in test mode, which is cycle up and down every few seconds in time with some relays clicking in the center console,
The car is very difficult to start when cold, misses, acts like is has some bad plugs, which it might as it is time to replace them.
And my daugther has described some kind of random squeaking noise from the front of the engine, which I have yet to hear long enough to diagnois, but I think it is unrelated.
Expert:  George H. replied 4 years ago.

This does sound like the computer has packed it in and is operating in failure mode which will allow you to run the engine enough to get to a place of safety and service. It will not run indefinitely though.

 

I would spend the diagnostic money to have a shop with a Select Monitor try to communicate with the computer. Call ahead and ask specifically if they have a Select Monitior as the aftermarket tools most shops have will not comunicate even if the computer was working properly.

 

I didn't ask if this is an automatic trans or a manual but the break point on the computer is threefold if you have an auto, before 7/92, between 8/92 and 9/92 and after 9/92 so if you have an auto trans it is not likely that the '92 is going to run your car.

 

If you search at car-part.com you can see what yards in your area have computers.

 

As always let me know what I can do to help you with this

 

thanks

 

 

Customer: replied 4 years ago.
George
we have a little problem here, I beliive you mixed up your wires. I checked with my local Subaru mechanic this morning and he said that the green connectors are for test mode while driving the car and the black connectors are for reading the flash codes, So I connected the black connectors and indeed the flash codes displayed.
So maybe you could salvage this by telling me what the codes mean.
First number as you indicated was a 12, that was followed by 13, then two long flashes and a short, which I interpreted as either 111 or 21 and then lastly 12 again.
Thanks
Chris
Expert:  George H. replied 4 years ago.

I don't think my information and memory was that faulty but I am glad you were able to get the codes.

 

graphic

 

graphic

 

A code 12 is a faulty starter switch which is likely not a "real" code but was induced while you were trying to read the codes.

 

graphic

 

 

 

Code 13 is the cam angle sensor. This is a high failure item and you can get the cam and crank sensors as a set from you dealer for less than either alone

 

CHECK CAM ANGLE SENSOR

  1. Disconnect cam angle sensor connector.
  2. While cranking engine, check that voltage between connector terminals varies synchronously with engine revolutions (0.1 V min.).

CHECK HARNESS BETWEEN ECU AND CAM ANGLE SENSOR

  1. Disconnect ECU and cam angle sensor connectors.
  2. Measure resistance between ECU and cam angle sensor connectors as follows: Connector

    & terminal:Resistance:
    (B58)4 - (B17)10 Ohm
    (B58)5 - (B17)20 Ohm
    (B58)6 - (B17)31 Ohm max.

    Measure resistance between cam angle sensor and ground as follows: Connector

    & terminal:Resistance:
    (B17)1 - Ground1M Ohms min.
    (B17)2 - Ground1M Ohms min.

    1. Connect ECU connector and measure resistance between cam angle sensor connector terminal (B17)3 and ground. It should be 1 Ohm maximum.
    2. Disconnect crank angle sensor and measure resistance between connector terminal (B18)3 and ground. It should be 1 Ohm maximum.

     

Code 21 is the coolant temp sensor (another high failure item)

 

 

CHECK ECU VOLTAGE
With ignition "ON," measure voltage between ECU connector terminal (B48)7 and ground. It should measure 0.6 - 4.5V .

CHECK COOLANT TEMPERATURE SENSOR

Coolant Temperature Sensor Testing


Disconnect sensor connector and measure resistance between sensor terminals. It should read as follows:

Resistance:Temperature:
2.0 - 3.0K Ohms20°C (68°F)
0.3 - 0.4K Ohms80°C (176°F)

CHECK HARNESS BETWEEN ECU AND COOLANT SENSOR

  1. Disconnect ECU and coolant sensor connectors.
  2. Measure resistance between ECU and coolant sensor connectors as follows:

Connector & terminal:Resistance:
(B48)7 - (E7)10 Ohm
(B48)21 - (E7)20 Ohm

  1. Measure resistance between coolant sensor terminals and ground as follows:

Connector & terminal:Resistance:
(E7)1 - Ground1M Ohms min.
(E7)2 - Ground1M Ohms min.

 

I am sorry if I offered confusing advice, that is surely not my intent.

 

Please let me know what I can do to help you with this

 

Thank you

 

 

Customer: replied 4 years ago.
Thanks, I'll check it out see if it works...btw..if you look back at your answers you specifically said to connect the green connectors and then in a subsquent post to make sure that the black ones were disconnected. So either the 93's on the west coast are different or there was mistaken info.
Sounds like the sensors you idenified will do the trick..especially with the fans running.
I'll let you know how it comes out.
Merry Christmas and a Joyous Holiday
Chris
Customer: replied 4 years ago.
Just read through your most recent answer carefully and it does indicate that the green test mode is used with the engine running and the car being driven. The black says it is for reading the memory. So that is where the confusion is.
Could you tell me where the ECU and the cam angle sensor are located, I don't have a book on this car.
Thanks
Chris
Expert:  George H. replied 4 years ago.

Sure,

 

The cam sensors is on the front of the head and the crank sensor is in the center of the block just above the balancer. Makes them easy to get to.

 

 

If you have a code for the coolant temp sensor (code 21) that is likely why your fans are running all the time, if it is shorted or the signal wire is shorted to ground the computer thinks the engine is hot so it turns the fans on.

 

graphic

 

Let me know what information you need and I will be happy to provide it

 

Thanks

 

 

 

George H., Subaru Certified Technician
Category: Subaru
Satisfied Customers: 15355
Experience: ASE Master Tech 15 + Years
George H. and 2 other Subaru Specialists are ready to help you
Customer: replied 4 years ago.
Thanks still need to know where the ECU is (emissions control unit I assume?)
Expert:  George H. replied 4 years ago.

The diagram was posted above, it is the MPFI unit next to the AT control unit if you have an Auto trans

 

graphic

 

 

Sorry if this was not clear

 

 

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