'04 Mazda B3000 ECU problem?

[SuperSalad]

So I had a problem a few months back where there was an electrical short and it ended up frying the computer in my truck. My mechanic replaced what was needed which required new keys (because of how the transponders inside the physical key link?).

This was back in may/june of this year. In the past few weeks I am getting an issue that I believe stems from the antitheft mechanism in the truck. As far as I can tell from reading online, the antitheft will basically shut down the truck if a key with the wrong transponder is used in the ignition. It acts like the battery is completely dead, but there is some signs of life if you know where to look. I know it isn't the battery for a few reasons. It is relatively new, shows no other signs of being bad, and it does work totally normally when I do the following.

It seemed to fire seemingly randomly if I turned the key just the right way, or something but I couldn't figure out anything for sure that worked. I tried all the 'fixes' I could find online to no reliable avail except for one. If I just disconnect the battery completely and reconnect it (even just a couple seconds of being disconnected), it fires up like there is absolutely nothing wrong. According to what I read, this quick disconnect just resets the computer. I don't know what is happening for sure though because sometimes the radio and clock rest and sometimes they don't when I do this.

I found a couple things online with people describing similar things, but I can't find anything that is exactly describing what I'm seeing. I'm calling my mechanic soon to see if he's got a solution, but in the meantime; anyone have a possible answer as to what this is?

 

[bdcardinal]

There is a transceiver that is basically a circle shaped antenna with a connector that goes around the ignition tumbler. That is a pretty common thing to cause a no-start on the Rangers and B-Series. That said, without getting it diagnosed we are just doing shotgun guesses (which I as a parts person paid on commission love).

Also you need to populate 2 key slots when programming a new PCM, so probably one of your existing ones could have worked. I just know that whenever I quote a PCM I also quote a key.

 

[01rangerxl]

The radio/clock keeps memory for a little bit when the battery is disconnected in my experience with my 2002 Ranger. Seems like a few minutes maybe. I know sometimes I don't lose anything if I'm quick, and I remember one time losing the clock, but not the radio presets. That may not be related to the problem you are having.

Did you get two keys and does it do the same with both? I got an aftermarket key made when one of my originals just got worn down and had to be jiggled in the cylinder. The aftermarket key worked for about a year and then quit. One day I got in the truck, turned the key, and just got a rapidly flashing "THEFT" light. My suspicion is the case on the aftermarket key wasn't sealed up very well and the resistor or chip or whatever is inside corroded. I verified it was the key by using one of the originals and the truck cranked right up. If it does the same thing with both keys though, I'd suspect something in the truck.

 

[SuperSalad]

Yeah I got two new keys with the work done a few months back. It happens with both, and neither already to be damaged or unsealed.

When the error occurs, the theft light flashes like normal until I turn the key. Then it usually stays solidly lit but not as brightly sand nothing else lights up. I haven't counted but it almost seems like it happens after a certain number of starts after each reset.

 

[SuperSalad]

So this issue finally came to an end and the whole truck went dead on Tuesday. Took it o my mechanic and the issue was embarrassingly simple.

It was corrosion on the battery nodes forming insulation. He said it was like a layer of eggshell he had to scrape off the nodes with a knife. Totally fine once it was removed. My removing of the connections and placing them back on must've jostled it just enough each time to reestablish a connection, but over time it spread and must have completely covered the node on Tuesday morning.

I had those things greased to high heaven when they were fresh about 2 years ago. I am shocked they were that corroded. Anyway, a successful ending I suppose and I am super pumped it wasn't anything more serious.

 

[zrxkawboy]

Thanks for the update, and glad it was an easy fix.