Electrical Issues: COR clicking, radio cuts out, truck sputters, headlights cut out...

So it started about 1 month ago. I was driving to work all was well and then I start to hear this clicking sound coming from the dash, the radio cut out, and then I started chugging and stalled... The truck wouldn't even crank over. So I ended up having to call a tow truck to come and get me.... It's a sad sight when a Taco is on the back of a flat bed.

Anyways, I left the truck for about a week before I had time to look at it. When I came back to it, it started right up like nothing had happened. It didn't seem to have any symptoms for about a week, but then it did the same thing again, but it didn't stall this time.

I finally figured out that it was the Circuit Opening Relay that is clicking, so I swapped the EFI with another relay that's the same to see if that was the issue, it wasn't. for the past month, the truck has been drive-able, but barely. It has the same symptoms, and the truck really stutters like it wants to stall, but it hasn't yet.

I just ordered a new COR that will be showing up today, but I'm thinking that, that's not the issue...

Any ideas?? This is going on too long! I want my reliable taco back.

(It's a 97' 2.7L 4cyl Taco with 400,000miles)

 

Just a WAG--check your battery connections and the ground connection from the battery to the chassis.

 

all that is good... checked that a few times

 

Have you checked your battery posts, terminal lugs and the battery cables? how about the battery health? Is the charging system able to maintain a full charge on your battery? If not, check the output voltage at high idle and AC ripple on the alternator at the output terminal. Depending on the ambient temperature, you should see at least 14 VDC (measured with a digital voltmeter) and less than 500 mv of AC ripple. Real weird or intermittent electrical problems are usually a high resistance ground connection from oxidation or corrosion, especially on vehicles over ten years old.

 

Boy, sure sounds like a bad ground to me.

 

Break out the multimeter and get some real world voltage readings

Looking at the cables and battery terminals is not checking them!!

 

So... We followed all of the grounds and couldn't find anything. I purchased a new COR relay... no changes. But here's the weird thing. When all of the symptoms start happening again we plug in our scan tool and all of the symptoms stop completely. If you unplug the tool, it all starts up again... We've tested it multiple times by doing that and every time, the scan tool stops the problem until we unplug it and then it starts back up again.

Any ideas what that could be???
Maybe the ECU?

 

Wow that is really different .

Well you narrowed it down to the OBD II connector and the wiring to the ECM

At any time could this have gotten soaked Heavy rain Water crossing ??

ECM`s tend to work well to they get wet

Maybe some extended driving with the scan tool plugged see if it continues to work ??

Just a idea

 

I don't think that the ECM got wet... We took the ECM out after all of this started and put it in the freezer to see if it would make it act up, which it didn't do anything noticeable or consistent after that. The ECM looked really clean when we took it out of the glove box area.
Also, we just did a 150 mile road trip in it yesterday and it would act up, then we would plug the OBD II in and it would stop, but if we unplugged the scan tool at all, the clicking, radio, and light flicker would start up immediately after we unplugged it. it we left it plugged in, nothing would happen. It would drive fine otherwise... It didn't sputter or die like it has in the past.

This is definitely a strange electrical issue.

I'll take all the info I can get from people on this issue.

 

Just to bring this thread to a close, we found out what the issue was! Like everyone said, it was a bad chassis ground. The wire was still attached but when I went to test it, the wire cracked in half. The Taco is running like a champ again (minus a bad vibration coming from the carrier bearing)!! Thanks everyone!

 

Glad you found the issue!!

Just goes to show the visual check of connections should never be trusted .