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So I’m under the passenger side dash attempting to back probe my ecu to see if I get any feed from my cps to the ecu when I spotted this hack. See attached photo. It appears the red and blue wires that are associated with the cps have been cut and spliced to a white wire and a black . The black should be ground but the white one does not show up in the wiring diagram. This wasn’t done by me and if I bought the car this way it was running fine with this set up. I will check for feedback anyway but it seem the blue wires that are would negate the red but I don’t know at this point
So I hook up a multi meter to the spliced area ,figuring I’d see some power getting to this point but when I turned on the car and cranked the engine the meter stayed at zero. So it looks like no signal is reaching the ecu. Any thoughts on t.his?thank you
Not all wires are for voltage, some simply go ground, so you'd want to check for ohms as well?
It does seem to be the shielded red wire that runs to your crank position sensor. I'd start by disconnecting that white added wire and see what happens. If the shielding is compromised, it could cause all sorts of problems.
I suspect someone thought they could pull some power off of that red wire, since red is typically the hot wire. In this instance, it most certainly is not. The voltage varies with RPM
You did look at all the input figures on Section 25 of the wiring diagram to understand what readings(s) you should be seeing on each of the input wires to the ECU, didn't you? As Vee has eluded, some input signals are Earth (Ground), some are 12v, some are even AC voltage and some vary with rpm. You must read that diagram page to know what you should be seeing on each input wire when its active.
You're looking at Pin 23 not Pin 26, aren't you? Pin 23 is a voltage signal input, Pin 26 is an Earth input.
From a quick look at the electrical diagram, it seems to say that the voltage input is an AC Volts signal, not a DC Volts. Have you got your multimeter set at AC voltage?
Yes it was set to 20 volts ac. I put an alligator clip on the junction of that hack splice and grounded the other lead. Cranked the engine and got nothing .meter read zero
Just a couple of observations, not sure if they may have been covered or not but just a couple of things I've found with a crank with no start. First the security system will cause a no crank due to the start inhibit circuit. My no start was found by checking the voltage at the fuel injection power relay. I found mine at 7v. Went back to the right hand fuse block to check fuse #7 15a fuel injection main relay, ignition system power. Found only 7v on the switched power side of the fuse, which would be the top blade. That low of a voltage will never allow any fuel injection system to run. I had to run a jumper from switched power under the steering column, large white wire to feed full 12v over to the top blade to energize that whole circuit. After that the car started right up with no problem.
If any of this has been previously covered, my apologies for any repetition. Just did have time to read through the whole post at the moment.
Well my fuse #7 on the right fuse block is listed as a 10 amp EMS power relay, Transmission relay. My car is a ‘95 so I know these fuse locations vary by year. I also don’t see a fuel injection relay listed as a separate item ???
Yes, I have a '95 and '94 6.0l which do have differences in the wiring. The cover over the fuse box should have a legend on it, at least mine do. This should identify ECU power circuit. Whichever one it may be is the one you want to check.
As shown in the picture I provided my 23 connection ,red wire, and my 26 connection blue wire are spliced together with a white wire? Coming off the harness and a thicker black wire,ground?, coming off the harness and a. How this would function at the cps I have no idea but it had in the past
But did you check the supply voltage? Is it getting to the power relay that turns on the FI system in the boot? Also, is there a full 12v across the fuse for the ECM? The ignition will not operate without it. Start there first as it will be easier to verify. If you have power there then move on to the next point.
Without power there, nothing else matters.
Last edited by Jagman99R; Sep 17, 2025 at 05:02 PM.
I had mentioned previously about testing whether you had (proper) voltage at the inputs of the EMS Power & ECM Controlled Relays. I don't know whether you did those tests?
However, the CPS is a Hall-effect sensor that generates an AC voltage. If that isn't functioning then consideration of everything else such as the Relays, ECU doesn't matter. You have to know that your CPS has continuity at rest and generates the right voltage signal when cranking. If it were my car, I would focus all my efforts there first. Start by checking for continuity at the sensor terminals AT THE SENSOR. Don't let any problems in the wiring loom confuse matters. I think I remember reading somewhere that it should be c1.37k ohms, but don't quote me! If that works, do the same test at the ecu plug terminals (disconnect the plug first). If that checks out, then see if you can check the AC voltage signal when cranking AT THE SENSOR, not the ECU plug. IF that works, do the same test at the ECU plug. You really have to verify this CPS integrity and signal first.
Ok so to do this test
1. unplug the sensor at the cps location
2. probe the red wire female end of the plug with a mutimeter set to ohms
3. crank engine and look for a reading
perform the same test on the blue side of plug
if i dont get any reading there ,check for 12 volts at the EMS fuse which is on the right panel #7 10 amp fuse
also check for 12 volts at fuses #10 ECM controlled power and fuse #14 ECM controlled relay
Last edited by wardhill68; Sep 18, 2025 at 09:40 AM.
Ok i dont seem to have continuity from the red wire side if the cps back to the ecu but i do have it on the blue wire. I will double check the quality of the splice in the attached picture
No, you just need to start by measuring the continuity of the internals of the crank sensor. No ignition, no cranking.
Just undo the plug of the CPS. Now with the multimeter set to Ohms, just measure the continuity BETWEEN the two terminals of the CPS with the two leads of the multimeter. Nothing to do with cranking the engine.
If you don't have continuity across the CPS terminals, I'd politely suggest your replacement CPS is duff.
If you have continuity at the CPS terminals, reconnect the plug at the CPS. Now disconnect the wiring plug at the ECU, and just do the same test BETWEEN the 2 relevant terminals of the wiring plug, the blue and red ones -pins 23 & 26 as I recall, of the ECU wiring plug. If you don't have continuity between those 2 pins, I'd now suggest there's a wiring loom problem from the CPS to the ECU plug.
However, If you do have continuity there. I'd now move to do another test on the voltage that the sensor generates.
I would disconnect the plug again at the CPS and by setting your multimeter to AC V, I'd connect the multimeter to the 2 pins of the CPS, crank the engine and check for the AC voltage. If you don't get the right reading, I would then check that the gap to to the toothed ring is correct. If so, I would remove the sensor, and do the same test using a bolt or similar and just move it forward and back in front of the sensor head whilst reading the AC voltage. Again, if you don't get a reading, I'd suggest the sensor is faulty.
Don't even worry about the fuses and relays yet. If this sensor doesn't work properly, your car isn't going to spark and start. The sensor generates its own voltage, by the teeth of the ring gear passing in front of it. It doesn't need the ECM fuses or relays working to do that.
Ok i got the meter to read ohms at the sensor plug and at the ecu connection. The reading was bouncing all over the place most likely because im doing this wfith my one good hand but at least it indicates continuity back to the ecu. I will move onto the next step and see if i can manage it. That cps plug is in the damdest spot.
