Bad ECM?

Ok... So I posted here a couple of months about about three sensors on my truck being stuck in not ready status. (1996 Toyota Tacoma X-Cab, manual) I've been patient hoping that it's just a drive cycle issue. Well I've gone over 2,000 miles and still no go. They are still "Not ready". I broke down and took it to a mechanic. They said that all of the sensors are testing fine and that it must be a problem with the ECM. He mentioned that the dealership might possibly be able to "re-flash" the computer. Otherwise I would need a new ECM. So I called the dealership and they said that they don't know of any flash update for my vehicle and to bring it in so they can look it up by VIN and see whats going on. They said that if they could flash it that it would cost about $125.00. Well I've looked around and I think I can find a used and tested ECM for about the same price. The problem is that I don't want to order one and find out that it doesn't work because it doesn't match my trucks features exactly.

What would you guys do? Any suggestions? HELP!

Thanks, Dante

Reply to
Dante
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During my time as a district service manager, I encountered exactly ZERO ECM's that were actually bad, and in speaking with the person who was in charge of the facility that tested and repaired ECM's that were returned under warranty, only 1 or 2 ECM's every 2 years or so were actually bad. In other words, it is literally something like a one in a million chance that the ECM is actually bad.

In most cases where changing the ECM fixed a problem, it was probably a loose connection between the ECM and the harness, and the process of swapping ECM's cured the problem.

My recommendation is that you unplug the ECM, carefully check each connector pin on the wire harness side, and then re-plug the harness into the ECM, and if that does not work, take a look at the factory service manual.

Drive cycles are specific to each vehicle so unfortunately, there is no generic drive cycle that will get any OBD II-equipped vehicle in a ready state. To make things more difficult, part of the drive cycle usually includes a specific time period where the vehicle is parked so if you don't park it long enough or too long, then the ECM won't acknowledge that the drive cycle has been completed. The specific drive cycle for your vehicle should be in the factory service manual, which you can access on line at techinfo.toyota.com for $10/day. While you are rootin around in there, the factory service manual will have hints on fixing your problem.

IMO,. a $10 investment to peek at the factory service manual is less $$ than buying an ECM that you may or may not need.

Reply to
Ray O

truck being stuck in not ready status. (1996 Toyota

issue. Well I've gone over 2,000 miles and still no

They said that all of the sensors are testing fine and

might possibly be able to "re-flash" the computer.

that they don't know of any flash update for my

on. They said that if they could flash it that it

used and tested ECM for about the same price. The

because it doesn't match my trucks features exactly.

that were actually bad, and in speaking with the

were returned under warranty, only 1 or 2 ECM's every

like a one in a million chance that the ECM is

connection between the ECM and the harness, and the

pin on the wire harness side, and then re-plug the

service manual.

generic drive cycle that will get any OBD II-equipped

cycle usually includes a specific time period where

the ECM won't acknowledge that the drive cycle has

factory service manual, which you can access on line

factory service manual will have hints on fixing

buying an ECM that you may or may not need.

I think it's a safe bet that everyone who reads this news group will agree with me when I say, FOLLOW RAY'S ADVICE! You could not get better advice in these areas....

Thanks Ray

Reply to
Danny G.

Thanks for the vote of confidence! Hopefully, the OP will find something other than a bad ECU.

Reply to
Ray O

I have a similar problem with my 2001 Corolla. So far, after clearing the code(P0420), 1 month has passed and ODBII reader still shows that CAT cycle has not done yet. I agree with Danny's comment about Ray.

Reply to
wenmang

Reply to
mrsteveo

Ray,

The ECM in my 93 Toyota pickup went bad. The dealer had the truck for over 2 months while trying to diagnose the problem. Finally they diagnosed it as the ECM by swapping it with one from another truck. Then they wanted to sell me a new one for $1100.00. I replaced it with one from a junk yard for $125.00 and all is well.

Q

Ray O wrote:

Reply to
Q

I've run across that scenario a few times, where someone tries everything except the ECM, and when they finally swap the ECM, the problem is solved. When the ECM is sent to the lab for testing and repair, they do not find anything wrong and when it is re-used, the problem never appears. According to the head guy at the lab, the process of unplugging and re-plugging the ECM seems to cure the problem. Like I said, they do run across one or two that test bad every year or two, it sounds like yours was one of the rare failures. Have you played the state lottery lately? ;-)

Reply to
Ray O

Ray,

Yes, this one was truly bad. When they plugged my ECM into the other truck, the other truck ran just like mine did. Also I had the ECM out several times to check the connectors, wiring, and internal soldered connections. I suspect a bad power transistor that drives the ignition coil/ignitor.

Q

Reply to
Q

So I finally got it to recognize a drive cycle.... (Thanks Ray for the suggestion of downloading the drive cycle from Techinfo.toyota.com) The check engine light came on. The code is P0130. Malfunction with heated o2 circuit bank 1 sensor 1.

I ran a couple of tests on both o2 sensors and both of the heater elements measure about 12 - 16 ohms. The Hayes manual says that they should only be about 5-8 ohms or so.

My question is what should I do from this point? Should I just replace both sensors? Could it be something other than the sensors?

By the way... the previous owner must have bottomed out while going offroad or something because the downstream sensor is slightly bent and a little of the wire is showing through the insulation.

Thanks in advance, Dante

Q wrote:

Reply to
Dante

Could you care to share some info with us? My 2001 Corolla currently stucks with CAT monitoring cycle and 1 month passed and the drive cycle is still not complete. What kind of info(or trick, not specific info) given by Techinfo.toyota.com which can allow ECM recognize the CAT drive cycle? I am only interested in how to make CAT drive cycle complete. Can the viewed material be printed on printer and what kind of key words that you use for searching? Thx.

Reply to
wenmang

I had to subscribe to a one day memebership to techinfo.toyota.com. There you can find any information you want about your specific vehicle. I would advise doing just that. You can download the documents that you find and save them so you can print them for future use... It's well worth the $10 bucks. I would love to help you but the drive cycle for a 1996 Toyota truck is most likely different from that of a 2001 Corolla. Basically the drive cycle that I did consisted of a) driving at a steady speed then b)stopping and idling for a few minutes, then repeating a and b again. I did have to do the cycle two full times with an engine shutoff in the middle. Hope this helps.

Dante

snipped-for-privacy@yahoo.com wrote:

Reply to
Dante

Thanks. I will do the same(1 day subscription). Are you searching "drive cycle" on techinfo.toyota.com, right? I just like to quickly locate the info I need. Thx.

Reply to
wenmang

On the left side of the page (after you have logged in) there is a place to select the types of docs you want. I believe that it was a technical bulletin. I checked that and then ran the search with an empty field to get all of the bulletins for my vehicle. That's it.

Good luck!

Dante

snipped-for-privacy@yahoo.com wrote:

Reply to
Dante

If both O2 sensor heaters check out bad, then the sensors need replacement.

Reply to
Ray O

That's what I was thinking too... I just hate to spend that much money to find out that it's not really a problem. So I will replace both sensors... Anything else I should be looking for?

Reply to
Dante

I forgot to add that I gave that advice assuming that you checked the O2 sensors at the sensor pigtail and not at the ECM. If you checked at the ECM, then check for high resistance in the circuit between the ECM and where the O2 sensors plug in.

I recommend OEM sensors, but if you decide to go aftermarket, then save the pigtail off of the old sensor and splice it to the aftermarket sensor, if a splice is needed. I recommend soldering the splice and then use shrink tubing to insulate the splice.

Reply to
Ray O

Thanks for the heads up. I did check it at the pigtail. So I've heard that Bosch is not the best brand to use with Toyotas... Is there any truth to that? What brand do you guys recommend? Also, with the shrink tubing, is a blow drier hot enough or do you need a heat gun... Or would something else work?

Reply to
Dante

The only experience I have with O2 sensors is OEM so I cannot say whether other ones are good or not. I suspect that the life of aftermarket sensors is not as long as OEM sensors, for example, the O2 sensors on our '97 Avalon with 110,000 miles are original. If they failed tomorrow, I know the OEM ones will probably last at least that long so I would go with OEM. On the other hand, if I were going to sell the car next year, I'd go with the cheapest solution.

As far as heat shrink tubing, a hair drier will probably take a long time to shrink the tubing. If you do not have a heat gun, use a lighter or a candle for heat, just hold the flame far enough away to prevent burning the insulation, like 3 or 4 inches, and keep the flame going back and forth.

Reply to
Ray O

Mad thought: how about wrapping the tubing in alumin(i)um foil to several thicknesses of foil during heating? Close off the foil's ends to ensure the very hot air stays inside.

Reply to
Andrew Stephenson

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