Trick30

so in my 1992 pickup 3.0 the check engine light was on and the guy i bought it from said it was for an 02 sensor. but then i found out my truck is running on only 5 cyls, so i though that would of been why the light was on. but i put a ne battery in it today and the check engine light has yet to come on? does that lean towards 02 sensor? or is there a plug somewhere for my scanner tool? i searched and searched. i have no clue.

wyoming9

iTrader: (1)

Sorry nothing to plug your scanner into on the OBD I system

Although there is a thread on here about that I have not followed

Could be since you cleared the codes it just has not tripped yet

All that gas being dumped in a cylinder not firing is not good

scope103

bcd? Binary-Coded Decimal?

"How to read codes" is answered about twice a day on this forum; if you'd spent a few seconds looking around first you would have found this:
http://web.archive.org/web/201211190...85diagnosi.pdf (The Special Service Tool is a paperclip.)

Removing the battery WILL clear the codes, so it's just a matter of time until it comes back. When it does, read the codes, and fix them. Yes, even if it's "just" an O2 sensor, ya gotta fix it.

millball

There certainly are scanners that exist that plug into Toyota OBD-1 plugs.

The dealers have/had, a factory service type device, and Snap-On and others made High-dollar diagnostic scanners that could interface with the non-standardised early OBD systems made by most car manufacturers before OBD-2 became standardised.

I have a Snap-On MT-2500 scanner that I use on my '87 and on my '95 4Runners.

It not only shows stored codes, but can show many sensor values which helps greatly in troubleshooting. I was able to use it to easily adjust my '95s' TPS with the engine running when I needed to.

Although both the '87 and the '95 are OBD-1, I recall that the '95 will give out more information than the '87 will.

I could have never afforded the Snap-On scanner when it was new, but they can be got for much smaller money now that they have been superceded by newer scanner models.

RJR

The '92(or '93, not sure which) and later vehicles will put out a proprietary digital data stream from the diag connector with info on TPS, VAFM, RPM, injector timing, ignition timing, ECT, vehicle speed, and some other stuff. That's what the more sophisticated scanners are reading. I wrote a VB.Net program to use a serial port on my laptop to do the same thing.

scope103

"Scanners" that plug into the OBD-1 port are sometimes electrically no more than a paperclip; you still read the flashes at the CEL. Since the CEL is electrically connected to the W pin on the diagnostic connector, a slightly more sophisticated model counts the pulses on the W pin for you. Easily worth the $0.08 you would have to pay for a paperclip.

The MT-2500, I believe, DOES read the proprietary Toyota OBD-1 stream. Since the MT-2500 is about 25 years (!) out-of-date, you can pick up one for a few hundred dollars on eBay (don't forget to get the right software cartridges).

But, if you're a YotaTech fan, you can build your own true scanner for approximately $5; you just need the software written by our very own RJR: https://www.yotatech.com/forums/f116...reader-278801/

(I've not tried it yet, for no other reason than I need a laptop with a serial port. I wonder if he "copied" it from some Russian software I saw a few years ago.)

Alas, the OBD-1 data stream only refreshes about every 1.25 seconds, so it's not a big help compared to directly monitoring values.

RJR

I didn't copy it from the Russians. Somewhere I found an on-line a description of the data format, and from there it was a SMOP (simple matter of programming.) I used a USB to serial port adaptor I bought years ago from Radio Shack for $30.

While the data stream is slow, it is useful for troubleshooting sensors such as ECT, VAFM, and TPS. You can see exactly what the ECU thinks it is seeing, not what the sensor thinks it is sending through perhaps faulty wiring. For example, a TPS with dead spots is easy to spot just by slowly moving the throttle (with engine off) and watching the readout. Same with VAFM.

My '94 3.0 is running so well these days that I don't get much of a chance to do any serious diagnostics, but I'm sure the time will come.