83

It's official. At 299,450 miles I got my first check engine light.

I brought it to OReillys (which might be part of the problem) to have them read the code. The gauge would only say it couldn't establish a connection, or something along those lines. Is there any trick or tip that he may not have been aware of?

I brought it home and tried the paperclip in E1 - TE1. Key in "on" position. The check engine light stayed steady, didn't flash at all.

Any thoughts? I'm brand new to this so I'm sure there's a very simple thing I'm missing.

millball

Any generic OBD 2 code reader should work on a '98 Tacoma.

83

I've considered buying one, but never needed it until now! Is there an order of operations the auto store guy didn't follow? Does it matter whether you connect the reader first, before turning the key to "on"? Honestly I can't remember which way we did it now...but I assumed he at least had that part figured out, assuming it matters.

I'm heading out of town tomorrow, not far, but ~120 interstate miles. Just wanted a quick answer as to whether the check engine light is telling me I'm getting terrible gas mileage, or telling me there's something serious I should tackle before taking it out at 80mph for two hours.

Is there more to the paperclip thing that I'm missing? Or did I just not get a good enough connection and need to try again? Etc.

Thanks.

A friend in the town I'm driving to tomorrow has a code reader, and I'll hit him up for it, but I still need to drive two hours to get there...

millball

The scanners I know, give step by step when you power them up. I'd think an auto parts person would know how to use their instruments, but maybe not.
It's hard to get competent help.

On the bright side, many check engine light codes are emissions equipment related, and have little or nothing to do with actual engine management.

If you are not seeing any performance changes, you should be good to run it a little.

Jomoka

On my wife's '96, it wouldn't pass an annual state inspection one year since the state code reader couldn't connect. After some diagnosing, it turned out that one of the pins was supposed to be grounded, but wasn't. Never did figure out why, we just grounded that wire and it was back in working order again.

83

Interesting. Ok. Well I'll hope for the best on my drive and dig into it deeper with my friend. I do feel like my gas mileage is suffering lately, but being winter, with the cold weather, sand bags in the back and regular use of 4wd, I usually don't concern myself as much with that.

I still haven't fixed my catalytic converter exhaust leak, but it's been leaking for months now, so I'm not sure that would trigger it. I replaced the O2 sensors just before replacing the cat. But no point in brainstorming all the possibilities before getting a code to narrow it down. I'll unhook the battery and see whether the light comes right back on again or not.

fierohink

I would try a different auto parts store code reader. Or go back to the same one and plug it in yourself. Maybe plug and unplug it a few times to rub off any surface corrosion that may have formed. Those copper contacts can oxidize a bit over the last 25 years.

also the cheaper the scanner, the slower they are to read. I have a cheap-o $20 one that rides around in my glovebox that takes several minutes to establish a link.

83

Ah! Ok. Good to know.

Two updates. The check engine light has not come back on since disconnecting the battery, and my friend's reader only has the later-style connection for under-the-dash ports, so no luck there. Still, I'm in a different town with different part store employees, so it's worth trying them again.

This is getting way into beginner stuff, but my friend and I both noticed that while the wires coming out of the port are grounded, they're grounded to the head, along with wires coming from somewhere else on the engine. Obviously this must work, but I didn't think grounding to aluminum was a good idea. ?

millball

Your 1998 Tacoma should have an OBD II

port under the dash about in line with the gas pedal.

The port under the hood is a throwback to the earlier Toyota diagnostics.

2ToyGuy

Actually, aluminum isn't a bad conductor at all. Remember, house wiring was aluminum for a while during WWII, as "they" used all the copper they could lay their hands on for "The War Effort".

Spark plugs are grounded through aluminum, and they need a good ground to get a strong spark. That's one reason the ground from the head, on the bolt holding on the driver's side lifting hook, to the body metal behind the head, is so important. Another being the alternator ground goes through the head.
Two critical systems, sharing their ground through the aluminum of the head.

My usual, long winded, babbling, sorry. Hope it answers your question, through. Aluminum is a decent conductor. Not the greatest which is gold or platinum, but nearly as good as copper. Look at where the two lie on the periodic table. Very similar metals, as far as electricity is concerned.

Have fun!
​​​​​​​Pat☺

Jomoka

/\ /\ /\ /\ This. I assumed you were plugging it into the OBD2 port under the dash. An OBD2 reader isn't going to work with that diagnostic port under the hood.

83

Sorry, when I read that I did one of those "d'oh"! things for which there seems to be no emoji...Then kept forgetting/procrastinating actually checking my truck. Sure enough, there is a port in that location. Facing down towards the floor. I had heard the engine-bay diagnostic port mentioned over the years, and noticed it there, so I always assumed that was my one and only port.

Still no check engine light, but I'll eventually bring it back to the parts store to see if there are any stored codes. Unless unhooking the battery resets them?

millball

Disconnecting the battery DOES reset them.

2ToyGuy

Also, most of the check engine codes are on what Toyota calls a "two-trip" setup. IE: the problem has to show up on two consecutive separate trips before the ECU will set the code, and check engine light. Toyota went to this when they started using the OBD II system.
So, if you reset the codes by pulling the battery lead(s), and then drive down to the parts store to get the codes read out, you may not have any codes set. You would need to drive, say, down to the grocery store, go home and shut down the truck, and then that after noon, or whatever, drive it down to the parts store and see what codes are set. Two trips, not just two separate starts, you see?

Just thought I'd mention this. Hope it's some help.
Pat☺

Wainiha

My Scangauge II is mounted on my steering column and always plugged in. It works for codes and has various gauges that dash panel doesn't.