'86 MJ 2.5L ECM....good?

[eaglescout526]

Well it is entirely possible the ECU isn't extending the ISA like it should, we will have to test voltage to see if the ECU is extending it or retracting. D2_11 is extend, D2_14 is retract and D1_3 is the ground. Which mean we will have to do another fuel down the TB test and observe extend on one start up and retract on another, we will be looking for voltage greater than our baseline. I am willing to bet the ECU is trying to extend it.

[SoCalManche]

11 minutes ago, eaglescout526 said:

Well it is entirely possible the ECU isn't extending the ISA like it should, we will have to test voltage to see if the ECU is extending it or retracting. D2_11 is extend, D2_14 is retract and D1_3 is the ground. Which mean we will have to do another fuel down the TB test and observe extend on one start up and retract on another, we will be looking for voltage greater than our baseline. I am willing to bet the ECU is trying to extend it.

 KEY OFF:  D1_3 and D2_11/D2_14, both start at 0V.

KEY ON: Baseline for D2_11 and D2_14 are ~130mV.

While FIRING: Sporadic voltage, staying in the mV reading. They both react the same way. 

[eaglescout526]

Upon shut down of the engine, was there a voltage increase at D2_11 for the extend? If you happened to observe that?

[SoCalManche]

Just now, eaglescout526 said:

Upon shut down of the engine, was there a voltage increase at D2_11 for the extend? If you happened to observe that?

I don't think so, but I will go check again.

[eaglescout526]

Ok, we might have to try the ground probe in D2_7 rather than D1_3.

[SoCalManche]

3 minutes ago, eaglescout526 said:

Ok, we might have to try the ground probe in D2_7 rather than D1_3.

D2_7 provided the same readings across the board with KEY OFF / KEY ON / FIRE.

 

Luckily for you, I took a slow-motion video of what is happening. This was taken with D1_3 as ground, but the same applies with D2_7 as ground. It looks like it shoots up to 5+V at the end briefly, but I don't know if that's what you're looking for.

 

https://drive.google.com/open?id=14_K3jMBRF4caoAKcr804yVlBwfIvdf1f

[eaglescout526]

So it looks like the ECU is trying to extend it for warm up sequence. That was a good capture, probably wouldn't have seen the numbers. Alright that's enough of the ISA.

 

Well do we want to look at the B+ circuit? 85 goes to T7 and to D2 but the schematic doesn't say. 87 goes to D2_4(swear it should go somewhere other than there) and 86 goes to T19, so we can check for continuity. 

[SoCalManche]

7 minutes ago, eaglescout526 said:

So it looks like the ECU is trying to extend it for warm up sequence. That was a good capture, probably wouldn't have seen the numbers. Alright that's enough of the ISA.

 

Well do we want to look at the B+ circuit? 85 goes to T7 and to D2 but the schematic doesn't say. 87 goes to D2_4(swear it should go somewhere other than there) and 86 goes to T19, so we can check for continuity. 

T7 & 85 = Continuity, 0.2 ohms.

T19 & 86 = Continuity, 0.2 ohms.

D2_4 & 87 = Continuity, ~0.7 ohms.

 

Question: when checking continuity, is it supposed to be a single beep or is it supposed to be a continuous beep, like "continuity" would assume? All three of those were a constant tone, but I checked 30 & 86 with D2_4 for giggles and they also had a constant tone with 0.3 - 0.7 ohms.

[eaglescout526]

Yep, continuity is a constant tone, if you were to touch your probes together, it will beep until you stop having them touch. We have tested everything and so far everything works except the fuel pump prime, pump during crank and the ISA motor. 

I'm not sure what else to check and test. 

[SoCalManche]

2 minutes ago, eaglescout526 said:

Yep, continuity is a constant tone, if you were to touch your probes together, it will beep until you stop having them touch. We have tested everything and so far everything works except the fuel pump prime, pump during crank and the ISA motor. 

I'm not sure what else to check and test. 

Can you tell me what the voltage is supposed to be at the fuel pump harness?

[eaglescout526]

Should be around 12V. 

[SoCalManche]

7 minutes ago, eaglescout526 said:

Should be around 12V. 

Well then there's an issue if I'm testing properly;

 

With KEY ON:

If pump is disconnected, I get 7.9V with ground probe in A and power probe in B. When I connect pump, it drops to 4V.

[eaglescout526]

Is this with relay in socket? 

[SoCalManche]

Just now, eaglescout526 said:

Is this with relay in socket? 

Yes. Do you want me to do same test with jumper?

[eaglescout526]

Sure, lets see what happens. I wonder if theres something from the relay to the pump that would cause such a drop.

[eaglescout526]

Like I was saying early on, between the relay is two splices and two connecters. One of those could be corroded enough to cause issues.

[SoCalManche]

6 minutes ago, eaglescout526 said:

Sure, lets see what happens. I wonder if theres something from the relay to the pump that would cause such a drop.

Alright, same readout regardless of jumper or relay. 7.9V disconnected FP; 4V connected FP.

 

6 minutes ago, eaglescout526 said:

Like I was saying early on, between the relay is two splices and two connecters. One of those could be corroded enough to cause issues.

Is the first connection closest to relay the six-pin connection?

[eaglescout526]

So according to the schematic, from 87 on the relay, it goes to a splice, then from the splice it goes to the fuel injector, EGR solenoid and Connector 113 which is a four prong plug. There is also a C114 which looks identical to C113 but C113 should have an orange wire that leads to a splice that feeds a load swap relay, PS switch and to C100 which is the bulkhead under the clutch master cylinder, then from there it goes through the cab to the fuel pump connector.

[SoCalManche]

18 minutes ago, eaglescout526 said:

So according to the schematic, from 87 on the relay, it goes to a splice, then from the splice it goes to the fuel injector, EGR solenoid and Connector 113 which is a four prong plug. There is also a C114 which looks identical to C113 but C113 should have an orange wire that leads to a splice that feeds a load swap relay, PS switch and to C100 which is the bulkhead under the clutch master cylinder, then from there it goes through the cab to the fuel pump connector.

Looks like The Unicorn may have struck again. So as I sifted through the engine bay, I found the first spice, at it looks to be intact;

https://drive.google.com/open?id=14d7HdLo9m2vOjlxLRrpk8n0eWsVqhgA5

 

I only have two four-pin connectors, one of which was in that mess I showed you yesterday when I started pulling split loom (https://drive.google.com/open?id=14g04avjIx-mICUV7cZyuw-4Re3OnDnqG) and then the other four-pin (https://drive.google.com/open?id=14iHlCH-FUWGw6smlrAH4yPlXhjJopyTr) I have in the engine bay is right by the battery, and looks to plug directly into that third relay (I think you said it is power steering?); also looks like the green and white wire has a little chip out of the wire insulation.

 

Then, if you follow the harness around the block, it comes to another splice right before heading into the firewall;

https://drive.google.com/open?id=14fJ-ZdS5fBxF77who01daJSDdm8mCpdS

 

That's what I'm dealing with.

 

[eaglescout526]

First splice should go from 87(one wire) to the splice which branches off four time, one to the EGR, one to the FI, one to D1_6 and one to C113. Then from C113 an orange wire goes to another splice of five more orange wires with a connector going nowhere and four going else where and to C100(bulkhead connector) But the second splice should be orange wires, not black so I am not sure about that second splice. 

 

I can't seem to find C114 in the schematics but it isn't under engine control. Do both connectors have an orange wire or just the one? If just the one that is the C113

[SoCalManche]

1 hour ago, eaglescout526 said:

First splice should go from 87(one wire) to the splice which branches off four time, one to the EGR, one to the FI, one to D1_6 and one to C113. Then from C113 an orange wire goes to another splice of five more orange wires with a connector going nowhere and four going else where and to C100(bulkhead connector) But the second splice should be orange wires, not black so I am not sure about that second splice. 

 

I can't seem to find C114 in the schematics but it isn't under engine control. Do both connectors have an orange wire or just the one? If just the one that is the C113

I'll let the video speak for itself, ha. (I kept saying orange wire with black wiring, but meant to say orange wires with black lines)

 

https://drive.google.com/open?id=14kY3Gwq3aaN7gohK1xHTWFttb-Cf-4U7

[eaglescout526]

Ok so that was splice "K" to EGR then FI then runs to the D1_6 in that mess and to another splice probably hidden in that mess. I am willing to bet the black splice is a ground, maybe like the CTS and ATS sensors ground, they do share a ground and splice in wire color brown with tracer. Then theres two other ground wires from the ECU that go into a splice that go to G110 and D2_7 on a black wire.

[SoCalManche]

1 minute ago, eaglescout526 said:

Ok so that was splice "K" to EGR then FI then runs to the D1_6 in that mess and to another splice probably hidden in that mess. I am willing to bet the black splice is a ground, maybe like the CTS and ATS sensors ground, they do share a ground and splice in wire color brown with tracer. Then theres two other ground wires from the ECU that go into a splice that go to G110 and D2_7 on a black wire.

Do I need to test those splices at all for anything?

[eaglescout526]

You can test for resistance and voltage and see if theres a drop.

[SoCalManche]

9 minutes ago, eaglescout526 said:

You can test for resistance and voltage and see if theres a drop.

So a few things happened:

 

Forgot the fuel pump was disconnected. Tried to crank with fuel down TBI and relay in, and it would not FIRE.

While disconnected, I was checking voltages, ground at Batt Neg and power at 87, and was getting 10V; 30 was Batt voltage. The first splice was also 10V.

After reconnecting pump, it fired back up no problem until fuel burned off. With KEY ON, 87 reads like 1V. Resistance is 0.L at 87, and flutters back and forth between 0.L and 0 ohms on that second splice (black splice). Second splice also had 4V with KEY ON.