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.

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.

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

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

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.

Thank ya! Shame, ISA motor might be chunked, but we ruled out a completely closed throttle being a problem. But we still don't have the fuel pump running when cranking with the relay.

Sounds good and will do!

SatiricalHen is going to a salvage yard tomorrow for some cruise control stuff, he says he knows where an 86 2.5L is, so he said he will snag the ECU from it. Id pretty much go through the wiring before you drop in a new ECU just to prevent the same issue from happening to a new to you or reman ECU. I mean I still think it is something in the fuel pump circuit but we are running low of things to test. You should pour some fuel down the TB tomorrow and see if the ISA will function after shut down.

I meant on the B+ relay, pin 30 on both relays should go right into a fusible link. This is tons of fun!

Yeah the book shows you how to locate it and remove it. I am not sure what would happen if we jumped the 30 to the 87 though.

Check the B+ relay. Check the wire harness and connectors, repair or replace as necessary. But the possible cause of the B+ would be no battery voltage applied to the injector(12V from one pin to the chassis ground). That's what the book says, but nothing on how to test it.

Theres nothing on the starter relay to test....I wonder why the book would say to look there. I just looked at the electrical schematics for the relay and fusible links and only saw the one fusible link for the ECU, FP relay and B+ relay. So theres nothing on the starter relay to give power to.

Yes I am.

No its not saying to have a wire go to the FP relay, but on the starter relay is also a terminal that triggers the fuel pump to run during start up. I do not know which terminal that is.

Ok so no trouble with that circuit. So the relay should energize, still not sure why it won't do the prime sequence.

All it says is to connect positive battery to the pump contact on the starter motor relay. Doesn't say how. So my guess is it is a spade connecter and not one of the fusible links that is held down by the nut on the relay.

Pin 85 to T6 86 goes to the ignition switch.

Yeah back probing is a PITA sometimes and contact with the metal is fuzzy. Just wait for the TPS adjustment. Well since theres no open circuit in either wires and 3k ohms would put the temp around 80*. So CTS and its circuit is good. Ok looking at more conditions in the book I got two FP will not operate for the one second Connect a jumper on the FP relay. Pump operates. You checked for continuity between the relay and T6 at the ECU connector for this one right? Then theres the checking for continuity between the relay and the pump, I remember talking about that one. Then theres test the ECU and pump ground circuit. Then theres the pump will not operate with starter engaged. Connect positive battery voltage to the pump contact on the starter motor relay If pump operates, repair or replace starter motor relay If pump does not operate, repair wire harness between the starter motor relay and the pump side of the ballast resistor. Not sure if that is for Renault models or both. Then it says to check the one second operation.

I like the 21 slot because it is different than what most others have and gives that more 80's look. But if I didn't have such I would do the 10 slot.

Is this back probed on the connector or connector unplugged? If we still can't get anything suspect a melted wire somewhere.

What if you did T32 and A?

Damn shame I don't have one of those to compare the video to. Well I will say it does go dim, not sure what pulsing should look like but it kinda looks like pulsing. I should get one of those lamps.

Alrighty. CTS test is as follows Located on the side of the intake manifold below the fuel lines and by the brake booster vac line. Testing resistance(ohms) with a volt meter The resistance should be less than 1000 with a warm engine, we can't get the engine warm.\ 212*F---185 ohms 160*---450 100*---1,600 70*---3,400 can't imagine the temp being lower than 70 so I won't bother with the rest of the chart. Replace sensor if it is not within the range of the chart above. Test the resistance of the wire harness between the ECU harness T15 and the sensor connector terminal, and T32 to the sensor connector. Does not specify which probe to put where on the sensor connector. Repair harness if open circuit is indicated.

Ok switches are good. Lets do a run down of what we have now. CTS and WOT switches are good. 5V are at TPS and MAP. Fuel pump runs but won't fire when jumped, engine runs with relay in place but fuel poured down TB. CPS is a bit below spec but is fine. Fusible link to fuel pump relay is fine as is ignition switch(we confirmed voltage on terminal 86 for FP relay right?). Fuel pressure is 15PSI. Engine has spark. Injector is less than 10ohms. Does the injector lamp pulse dimly? Do we want to test the coolant temp sensor?

Yes if both are external slaves. If one is internal and one is external, youll have to do some part swapping to get everything right.