1994 Toyota Tacoma check engine light

My 1994 “PreTacoma” 4 cylinder Extra cab four wheel drive pickup has hatched out a check engine light for the very first time in 225,000 miles.
Nothing is noticeable in performance or gas mileage. I changed the O sensor on the exhaust at about 125,000 and the distributer at about 200,000. Everything else is original. All the car part stores in the area don’t stock the old fashioned reader so I’m left with few options that are cheap which brings me to your column. In your guesstomation what would be a few likely causes. My brother had a 96 toy that he spent several hundred dollars on to eliminate the re-occurring problem and ended up with a real nice 3stooges pic to cover up the light. unfortunately he sold it with the truck. Thanks for your many years of entertainment and good advice. GC

Without the codes any answers from some folks on the internet would result in a series of guesses that would be more expensive to you than the purchase of an OBD1 code reader. You obviously have the internet. Use it to find a cheap code reader for your Toyota and post back so we can help you. You will be time and money ahead.

This vehicle uses “blink codes” . . . google it

I believe pretty much all pre-OBD2 Toyotas use a similar procedure to get them into the mode that spits out your code, via the check engine light blinking

Good advice, found the codes and instructions on how to jumper the diag. plug along with code descriptions. Strange thing though the ole Toy check engine prompt hasn’t came back on sense I started carrying the instructions and the jumper around. Guess she might be a little shy.

Ole trucks do get some personality. Thanks a lot!

Gary C.

Here’s how to pull the codes from your OBDI Toyota, and the code definitions.


I have an OBD I Toyota and read the codes every time I do a tune-up. Codes can be stored even though the CEL is not lit, so that’s where to start. The way it works on my 4afe engine, I jumper the test connector with the engine off, then start the engine. At that point the CEL blinks alternately, on and off. To get the codes to blink out, I step on the gas pedal briefly. I don’t think I’ve ever had a code other than “51”, which is the code that says the throttle position switch is working. If you disconnect the coolant temp sensor or the MAP, you should get a code, so that’s a way to test your method is working. Without the benefit of the diagnostic code, you’d just be guessing why that pesky check engine light is turning on.