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The 'Don't try this at home' thread

posted Oct 20, 2015 23:06:41 by Tyler
So another tech has a Toyota Echo in the shop with a lean condition. Tested all kinds of stuff, replaced intake gaskets, swapped parts from a known good car, still lean. I'm suspicious of clogged injectors, but no one has an injector pulse tester, and drop testing is not a bidirectional function on this Y/M/M. How can we do this test?

Why, borrow another vehicle that can drop test, of course! Another tech drives an '01 Silverado, comes with an injector drop test as standard. We get the Silverado and the Echo facing each other, run my super long test leads from a disconnected injector harness on the Silverado, and connect them to the corresponding pins on one of the Echo injectors.

Have one tech running the injector test on the Silverado, another on the Echo running the fuel pump between drops, and me moving the test leads around. It works! Of course, the injector drops were identical, so it was all a waste anyway. Figures.

Anyway, I always laugh at the stuff techs will do in the shop that is SO far from recommended procedure. Are we dedicated, or just stupid? Feel free to share your own experiences, I'd love to hear them.
[Last edited Oct 20, 2015 23:07:03]
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8 replies
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PaulDanner said Oct 21, 2015 17:45:19
That has to be one of the coolest tests I've ever heard of! Awesome Tyler
I had a low reference voltage problem on a flatbed Ford truck. (older EEC IV system). Ref circuit was around 1v. So he is stuck on the side of the road. I start testing for shorted sensors, none. Next I test the ref wire at the ECM, same voltage 1v. Next I check the ref circuit for a short to ground, no shorts.
Needs an ECM right? So to get him home I took my flashlight and removed its battery pack (it had 3, 1.5v batteries in series equaling 4.5v). and wired into the ref. circuit.
Truck starts up and runs good. No tow truck needed! Went to radio shack and bought a 5v reg. and wired it into his harness instead of replacing the ECM. He is still driving it today. :)
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Tyler said Oct 21, 2015 18:13:34
That has to be one of the coolest tests I've ever heard of! Awesome Tyler
I had a low reference voltage problem on a flatbed Ford truck. (older EEC IV system). Ref circuit was around 1v. So he is stuck on the side of the road. I start testing for shorted sensors, none. Next I test the ref wire at the ECM, same voltage 1v. Next I check the ref circuit for a short to ground, no shorts.
Needs an ECM right? So to get him home I took my flashlight and removed its battery pack (it had 3, 1.5v batteries in series equaling 4.5v). and wired into the ref. circuit.
Truck starts up and runs good. No tow truck needed! Went to radio shack and bought a 5v reg. and wired it into his harness instead of replacing the ECM. He is still driving it today. :)


Thanks man! Should probably add a disclaimer about how easy it is to cook a driver doing that procedure. Attempt at your own risk, ect...

Love the 5V regulator thing, especially since it's turned into a lasting repair. Makes me consider having one on hand for testing purposes.
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Noah said Oct 23, 2015 00:55:26
Tyler, that's genius! I may just have to keep a Chevy at arms reach.

My shop sold an 03 Explorer that would blare the horn and lights like it was being stolen whenever it felt like. I mean you could be driving this thing and it would just go nuts. It was waking up the neighborhood and draining the battery, just a complete nightmare.
After several comebacks, they sent it to a local electrical guru, who's best advice was to crush it after he tried changing a few modules.
So my boss was pretty sad over having to refund this guys money, after all we put 3 engines it before getting a good one. So I cheated it. I found where the anti theft module lived in the interior quarter panel and opened her up. Theres two relays soldered into the board, one blows the horn and the other flashes the lights. Well, they did until I removed them from the board.
Of course that was the only horn relay in the truck, so I soldered in one in the harness leading to the module so that it still works from the column, but the module can't control it.
So it's technically not fixed, but it's also not exhibiting any symptoms and they've been running it now for at least 6 months. Customer is happy, boss is happy and I got a bonus for saving the sale!
(That only worked because the theft prevention module and the immobilizer were two independent systems. Nobody could believe the truck still ran with the anti theft module murderized)
I hope they don't rescind my certs for that one!
[Last edited Oct 23, 2015 00:59:48]
Massachusetts, USA
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Tyler said May 16, 2016 00:51:49
Back from the dead!

So I just got done watching the 'How to test an ignition coil for control' Premium video, great stuff. Around 12 minutes in, ScannerDanner cautions his students not to use an LED test light in this application, and rightly so. BUT, I watched it during a slow day at work, and that's when I get in the most trouble.

"Whatever, it's Snap-On, it's got a warranty", is what I told myself. Despite the warnings, I just had to try it.

https://vid.me/3acx

It still works! There may be variables to this, like how this is a COP (and may not generate the same levels of voltage spikes), or how the test light used is a voltmeter/LED hybrid.

Unfortunately, I don't have a genuine LED test light, otherwise I'd try it. Not trying to call Paul out, saying he's wrong or anything of the sort. I just get that 'hold my beer' mentality sometimes ;-)
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AndyMacFadyen said May 16, 2016 06:59:38
About 10 years back I had a problem diagnosing an ABS fault an MG ZT, the system was a Bosch 5.7 with active wheel bearings and hall effect wheel speed sensor with the blue connectors similar to that on the BMW E46 320. I was the first time I had encountered the system and I had no diagnostic tools which would talk to the module, there was also zero information out on the internet and the car manufacturer had just went out of business.
Checking the system out with a volt meter pointed to the left front sensor, but changing sensor made no improvement. There had been signs of mechanical damage on the tip of the old sensor but I put this down to having to use excessive force to get the old sensor out. After I fitted the new sensor it passed the electrical self-test but illuminated the ABS fault light as soon as the car was driven a few yards. I tried another sensor - no change.

I then made up a proper breakout lead from junk yard parts and re-checked the three remaining wheel sensors uing the scope, when the wheel was rotated all 3 were putting out nice square waves.

By disconnecting the other wheel speed sensors and figured out on this model speedometer which was working okay was driven off the right fronr wheel speed sensor.

In desperaton suspecting a module or harness fault I extened my breakout leads and cross connected the right front wheel speed sensor wiring to the left front sensor and spun the wheel by hand --- no reaction from the speedometer or the scope. Then I pulled the new sensor out and passed a magnet close to it and got a signal on the scope and a reaction on the speedometer.

At this point after more internet research I came to the conclusion that active wheel bearing was damaged and debris and damaged the original sensor.

I found a low mileage a whole front left hub assembly from the local junkyard rather than pressout the old bearing --- job done :-)


[Last edited May 16, 2016 07:12:26]
"Rust never sleeps"
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Noah said Jun 14, 2016 17:01:37
Umm, what?
Massachusetts, USA
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Tyler said Jun 19, 2016 16:18:29
Ahahahahaha, YES. That picture sums up this thread perfectly!
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Noah said Jun 19, 2016 16:45:43
I know right? Must have ran like crap without the plug wire.
Massachusetts, USA
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