No Start (1 Viewer)

[bushak]

1KZ-TE

About a month ago it would take a cycle or two of the ignition to get it started, if I noticed no glue plug light I knew it wouldn’t crank, if I keyed off then on a few times once I got a light I would turn the starter and she’d run great.

Happened today where it took about 10 on and off got it going.. then I stopped again and it was off for good.

I initially thought glow system, I checked plugs, fuses etc. when I turn my key on the relay clicks, and I get a momentary spike, very momentary on the voltage going to plug rail then drops to 0.V,

I can crank and no start, after running down multiple glow wiring, and even manually jumping the plugs outside of engine to test and then with them in I still get no start.

I cracked a injectors line on crank and didn’t notice any fuel but I’m not sure how much it should be spittting. I’m going back to the truck in a day or two but I’m trying to figure out what to focus on.

I’m leaning towards fuel delivery at this point, but in can’t find anywhere where the spill valve or fuel pump not working would cause the glow to not fire at all… it was fairly cold out but the engine was still warm.

I’m going to check Spill valve relay for operation.
I’m going to try and check some pin outs on the ecu for proper function..

How common is the ecu toast on these?

Kinda a scratcher, don’t want to start throwing parts at it. All initial signs pointed towards new glow plugs but they all burn bright and ohm out around .7r..

the lack of fuel in my last check before I had to leave had me thinking something fuel delivery despite the glow plug light on dash still not turning in at all and in the past once I got that momentary flash, even if it was very short it meant it would start.

 

[apexwerks]

I'm biased, because I just performed an ECU swap... so take that in consideration.

I'd get out your multimeter and check everything... You've already done glow plugs, so that's a good start. Test your glow plug relay and your spill valve relay, test resistance on the spill valve. Visually check the ECU - it's easy to get to and bad components should be obvious (leaking caps, swollen caps etc). Then test pin outs on the ECU, the FSM has a pretty good set of diagnostic checks on the ECU and tells you where it should be sending voltage and when. If the glow plug relay tests good but you're not getting voltage to it, you know it's got to be a wiring issue or an ECU issue.

My issue was similar. I was getting next to no fuel at the injector intermittently. Everything was mechanically OK - no air in the lines, everything worked often enough that I knew compression was good etc. It ended up just being bad circuits in the ECU and incorrect signals to the spill valve.

 

[bushak]

Thank you, definitely considering ecu, and spill valve.

The one thing that’s baffling me from a systems perspective is:

1- I turn key on I feel and hear glow relay work
2- I see a spike of voltage go to the glow bar but retreats immediately to 0v

Questions about that:
Does the ECU own some control of the current going to glow bar?

And

Is there anything in the system that could fail causing the system to not function through a sequence?

The reason I ask that is because as this issue has snuck up on me, I would know right away if I was going to have a no Start condition if I didn’t get at least a quick flash of the glow light. So early on when this was usually a 2-3 on-off cycle before crank to start.

I’m curious on the behavior there and if a ecu could be doing that also.. cause it sure seems like a relay…

 

[apexwerks]

Thank you, definitely considering ecu, and spill valve.

The one thing that’s baffling me from a systems perspective is:

1- I turn key on I feel and hear glow relay work
2- I see a spike of voltage go to the glow bar but retreats immediately to 0v

Questions about that:
Does the ECU own some control of the current going to glow bar?

And

Is there anything in the system that could fail causing the system to not function through a sequence?

The reason I ask that is because as this issue has snuck up on me, I would know right away if I was going to have a no Start condition if I didn’t get at least a quick flash of the glow light. So early on when this was usually a 2-3 on-off cycle before crank to start.

I’m curious on the behavior there and if a ecu could be doing that also.. cause it sure seems like a relay…

As I understand it, there's some logic in the ECU that uses the coolant temperature sensor as an input to time the glow plug circuit on duration. My diagnostic path would start with the cheapest component - the relay.

1. Pull and bench-test the relay by applying 12v to pins 3 and 4, test continuity across pins 1 and 2. I've had situations where, either due to corrosion or a failing coil, the relay clicks but still isn't sustaining continuity.

2. Test coolant temp sensor. There a Mud thread here describing similar behavior on a 78 that came down to a bad temp sensor. The ECU thought the engine was always hot, so it never ran the glow plugs. The thread has the FSM process for testing the sensor.

3. Dig into the ECU and potentially repair/replace. This is most costly and hardest to know, so I'd leave it for last. I gave up and threw an ECU at mine and got lucky, but it's not a sound diagnostic procedure.

Good luck!

 

[bushak]

I’m going to guess this is my culprit, picture attached..

 

[apexwerks]

Well, that certainly needs to be corrected

Good luck!

 

[bushak]

Just need to find a repair or new ECU.

It would make sense that this was an intermittent problem until it finally gave way. Looking forward to getting the ecu fixed or replaced soon and hoping thats all she wrote.

B

 

[apexwerks]

Toyota will sell you a new one for $1,300. It’s part number 8966160860. The guy I bought my used one from has 2 left. Lots of folks try to replace the failed components, so that’s another option.