Check Engine Light, Trac Off, Code 51....what Does It Mean?

[leftfooter]

My 92 LS400 had been sitting for nearly 2 years undriven. When I returned I replaced the battery and it started straight up. There was about a quarter of a tank of Gas in it that had not been treated with any preserver. I added some fuel additive (Seafoam) and changed the oil & oil filter. I then drove it until the tank was almost empty (yellow Light on) and put $10 of the cheapest gas in Austin (So Stupid!). Almost Straight away the Check Engine light came on with the Trac off light. I pulled the code this morning and got a Code 51. (Problem in engine control system)

This is what I've found out so far:

CODE 51:

ENGINE MALFUNCTION DETECTION CIRCUIT

Circuit Description

If the trouble (trouble which causes CHECK engine warning

light to light up) occurs in the engine control system, this circuit

senses the trouble and prohibits TRAC control.

Diagnosis

Problem has occurred in engine (CHECK engine warning light lights up) when engine RPM is 500 RPM or more.

Trouble Area

Engine control system.

Harness or connector between ABS & TRAC ECU and engine & ECT ECU. (Short in TR5 harness).

Diagnostic Chart

Check the diagnostic code for the engine. If codes exist,

repair engine control system according to the code output. If CHECK

engine warning light remains ON but no codes exist, check for short in

all the harness and ECU connected to CHECK Engine warning light.

So, this all sounds very complicated & a little contradictory. If anyone could put in layman terms what this means, & what is the best way to rectify this issue, I'd really appreciate it.

Thank you all.

[billydpowell]

ABS/TRAC code 51 - I beleive this just means that the engine reported a malfunction or set the check engine light to on. The Trac ECU disables the Traction control while there is a engine malfunction. If there is no code in the engine system there may be a short in ecu, trac ecu, or the harness.

[leftfooter]

Thanks Billy. "If there is no code in the engine system there may be a short in ecu, trac ecu, or the harness."

How would I find out if there is a code in the engine system? I thought that Code 51 was the code, but is there a different way to find out the code in the engine system?

Thanks again.

[KeyKeeper]

Is there a separate ADL plug near the fuse box under the hood?

Is this the method you used?

OBD1 manual check

[KeyKeeper]

If you can find a buddy with an old snap on scanner you can use this:

Snapon connector OBD1

[landar]

Putting in the 'cheapest' gas you could find was not a stupid thing, very logical actually. $10 does not get you much gas so it would be easy to dilute if bad. BTW, how much seafoam did you pour in the tank? That stuff is not the magic elixir that many believe. It can actually cause some problems.

You have not yet expounded upon what exactly happened to the performance, if anything. The light coming on is perhaps meaningful and perhaps not. If the engine still starts and runs ok, then fill up with premium fuel, reset the code(you have it captured already) and watch to see if further issues crop up. If the engine now runs poorly, let us know how it is acting up. Who knows, it could be as simple as a loose gas cap.

Oh BTW, seeing that you have a '92, have you ever had the trunk wiring harness checked or repaired?

[leftfooter]

Is there a separate ADL plug near the fuse box under the hood?

Is this the method you used?

OBD1 manual check

Yes Keykeeper, This is the method. Sorry for delay in replying, I had to go out of town so haven't looked at the car since I posted.