1990 Dodge Ram Truck - Check Engine Light

Barry

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Sep 1, 2003, 12:16:01 PM9/1/03

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I washed my engine at the car-wash and when I drove away, the "Check
Engine" light stayed on. I have made extensive visual checks and find
no hoses (vacuum, etc.) have come off.I put in new spark plugs and the
engine runs smooth.

Daniel J Stern

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Sep 1, 2003, 12:21:34 PM9/1/03

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The first thing to do is to check for flash codes.

To check the computer codes:

With the engine off, switch the ignition key on-off-on-off-on, leaving it
"ON". Do not go to "start", just "on" during this procedure.

Watch the "Check Engine" or "Power Loss" light. It will turn on, then go
off, then will begin to flash-out any trouble codes that have been stored.
You count-up the flashes and pauses to determine the codes. All codes
are two digits separated by a short pause, and each code is separated
by a long pause. For instance, if it flashes:

flash <pause> flash flash

flash flash flash <pause> flash flash flash flash flash

flash flash flash flash flash <pause> flash flash flash flash flash

Then you have a 12 (one flash followed by two) a 35 (three and five) and a
55 (five and five). 12 as a flash code means "start of codes", 55 means
"end of codes" or, if by itself, "No codes stored. Check the codes and
report what you find.

DS

Barry

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Sep 1, 2003, 6:14:37 PM9/1/03

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Daniel J Stern <das...@engin.umich> wrote:

> The first thing to do is to check for flash codes.

We did as said. The codes we obtained were
36 and 37. Then we got a 55, which means end of codes.
Can you tell us what the codes 36 and 37 represent?

thanks

Daniel J. Stern

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Sep 1, 2003, 6:24:16 PM9/1/03

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On 1 Sep 2003, Barry wrote:

> We did as said. The codes we obtained were 36 and 37. Then we got a 55,
> which means end of codes. Can you tell us what the codes 36 and 37
> represent?

36: Air Switching solenoid circuit open or shorted. This is what diverts
output air from the "smog" (air) pump to either the upstream location (in
the exhaust manifolds) or the downstream location (in the catalytic
converter).

37: Part Throttle Unlock (PTU) solenoid circuit is open or shorted. This
is what allows the torque converter lockup clutch to unlock when you goose
the accelerator while already moving.

Sounds like you got some connections wet, or perhaps finished-off some
corroded ones, when you pressure washed the engine. Find the main power
disconnect -- it's the black, white or grey barrel-shaped connector
approximately 5 inches down the positive battery cable from the terminal
clamp. Lift the lock tab with a flat screwdriver and pull the connector
apart. Let it sit for five minutes or so, then plug it back together.
Start the truck and drive it around until it's at full operating
temperature. Then repeat the code check procedure. If you just get a 12-55
(or 55 by itself) the condition was temporary and cleared up when your
engine wash water evaporated. If not...time for some diagnosis!

DS

Jeff Potter

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Sep 4, 2003, 12:33:32 PM9/4/03

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"Daniel J. Stern" <das...@engin.umich> wrote in message news:<Pine.SOL.4.44.03090...@alumni.engin.umich.edu>...

Where is the location of the Air Switching Solenoid?