Help with building your Speeduino, installing it, getting it to run etc.
By Built2runmaybe
#70518
Hey all,

I’ve been finishing up a typical LS project. First one using Speeduino. I have the full ecu unit wired to the engine and I am able to read most sensor values such as TPS, IAT, CLT, etc. Output tests seem to work as well. I am having issues getting an RPM reading of any kind. Checked over my wiring and it is proper. I was previously using the Gen III LS Crank Position Sensor (24x), but after searching these forums I found users (Credit- PSIG and CjCalhoun85) who determined that the Gen III sensor, which uses 12v ref, behaves oddly when using a 5v ref supply.

So I purchased a Gen IV sensor (58x) in attempt to dodge this issue in dealing with the 12v signal coming from the 24x sensor. The Gen IV sensor uses 5v ref. Installed it onto the engine, and there is still no RPM value being picked up.

I have checked the jumpers for the Hall and VR pins on the board, and they are set for the hall setting to my understanding. I can provide pictures if needed, since I did not build this unit and am amateur at best when it comes to microelectronics.

I remember that in other mega squirt applications using this sensor (58x), they required a 1k pull-up resistor between 5v ref and the signal wire in order to detect RPM.

A) if I attempt to add the resistor in line, say at the sensor connector, will this damage my ECU unit?
B) will this work to get the 58x sensor to read RPM? Is there a definitive reason why it won’t?

Thanks for your time, will provide an update with any progress,

Built2Run
By Built2runmaybe
#70519
UPDATE 1

Despite the fact that I am running a new Gen IV 58x 5v Crank sensor, I am still running a Gen III 12v camshaft position sensor on the 5v ref. From further reading I see this can be an issue. I may purchase a new cam sensor that runs on 5v if I exhaust more options.

I have removed the starter for the upmtinth time and tested continuity and voltage in my harness, considering it is an eBay Chinese reproduce. I was getting the 5v ref voltage from the proper pin, and I had proper continuity between the signal wire at the ecu side and the sensor side of the harness.

I also tested with a multimeter and noticed all my other working sensors share continuity with the engine block itself, while that crank position ground reference did not. I have used a jumper wire on the ECU connector itself to jump one of the sensor ground pins (this one has most of my sensors on it) to another sensor ground pin (the sole crankshaft position sensor ground pin I designated to that ecu sensor ground pin earlier). In my infinite wisdom it seemed smart to give the crankshaft position sensor its own sensor ground pin entirely on the ECU. Maybe that is causing me problems.

I am currently waiting for my laptop to charge up before I head back outside. I have jumped the sensor ground pins to each other so hopefully if that is the issue it should resolve and I should get an RPM reading.

I still have to confirm whether or not I need a new cam sensor. I will update further with more findings after I do another crank test now and see if I get an Rpm Reading

Built2Run(maybe)
By Built2runmaybe
#70520
Craaaaankingggggggg aaaaaaaaaand….nothing. No RPM signal still, even after the jumper wire. In the diagnostic tooth logger there was also nothing. Not a spike in sight.

I think it maybe the camshaft position sensor at this moment in time. I think I’m gonna get the newer 5v version to run off of the 5v ref instead of the 12v version and come back with results.

If that doesn’t resolve the issue I’m not sure what will. My head is spinning. I still haven’t tried using a pull-up resistor at the sensor connector. But other than that I don’t have any more ideas.
By Built2runmaybe
#70522
UPDATE 2


after searching for some time, I have found some diagrams to help me understand better.


First and foremost, I feared that maybe the great LS sensor and the black LS sensor had different wiring arrangements, much like the cam sensors. However, both crank sensors are wired the same, except for the 5v input instead of 12v on the grey connector.

These are some basic diagrams I have found on the forum and some others as well. It seems that a diode is used on the input signal line when using the black !2v crank sensor. There also seems to be either pull-up or pull-down resistors. I have found diagrams that display both, maybe this will take some experimenting. This has all been to get the black crank sensor working, but what about the grey one? I thought because it was already a 5v sensor I wouldn’t run into any of these issues.

I plan on taking my unit out of the car and opening the ECU back up to look at the jumper configurations one more time. I’ll provide photos just in case I missed something.
Attachments
IMG_0724.jpeg
IMG_0724.jpeg (648.93 KiB) Viewed 760 times
IMG_0723.jpeg
IMG_0723.jpeg (1.79 MiB) Viewed 760 times
IMG_7505.png
IMG_7505.png (1.3 MiB) Viewed 760 times
IMG_7498.png
IMG_7498.png (1.39 MiB) Viewed 760 times
By dazq
#70523
Built2runmaybe wrote: Sat Jan 18, 2025 9:12 am UPDATE 2


after searching for some time, I have found some diagrams to help me understand better.


First and foremost, I feared that maybe the great LS sensor and the black LS sensor had different wiring arrangements, much like the cam sensors. However, both crank sensors are wired the same, except for the 5v input instead of 12v on the grey connector.

These are some basic diagrams I have found on the forum and some others as well. It seems that a diode is used on the input signal line when using the black !2v crank sensor. There also seems to be either pull-up or pull-down resistors. I have found diagrams that display both, maybe this will take some experimenting. This has all been to get the black crank sensor working, but what about the grey one? I thought because it was already a 5v sensor I wouldn’t run into any of these issues.

I plan on taking my unit out of the car and opening the ECU back up to look at the jumper configurations one more time. I’ll provide photos just in case I missed something.
The images 724 and 7505 are in effect the same just turned round. The pull-ups / down don't differ , the pullup in the first one shown is present on the second but as it is internal to the speeduino is not shown on the diagram .

The diode block is only needed on 12v hall , for 5v just the pullup/down resistors are needed.
By Built2runmaybe
#70599
UPDATE

i tried connecting a 1k resistor between 5v and the signal wire, still did not see any changes for some reason. However, when i connected the resistor in between ground and signal i finally saw a blip on the tooth logger. Finally!

And by ground, i mean chasis ground and signal (literally connected against the body of the car). The crank sensor ground wire and signal wire wired together with a resistor still gave me no values. But when i wired the resistor in between the signal wire and the ground chasis, I got a signal. The crank sensor ground is the only sensor ground pin connected to that port of the speeduino, all my other sensor grounds are on the second port.

Although I am finally getting a signal of some sort, i only get a "blip" signal upon cranking. One issue can be the fact that my battery is a used battery and may not be maintaining voltage to the ECU while cranking over. But when I spin the engine by hand I still only get that "blip" of a signal.

Ive read in other places this can be caused by a grounding issue. Maybe the vehicle is not properly grounded- I have the engine grounded and other parts of the body grounded as well.

I know sheilding can be an issue, but I dont think it would in this case. Shielding to my understanding usually is a problem when you get a signal and it is noisy. In this case it appears for a moment and disapears. Ill have plenty of time to reground everything all over again and rewire the body and engine once again. This time around I want to focus on getting the crank sensor opperating fully.

I have to rewire the car anyway because a small gas fire took out my harnesses. Any wiring gremlins I made before I have the oppurtunity to fully correct now. Oof
By Built2runmaybe
#70802
UPDATE:

The first sensor I brought was defective. Lucky me. Spent so long chasing my tail and…….

Still nothing.

I noticed that the crank signal pin for my speeduino is outputting 5v. I’m not sure if it supposed to do this, but that would make sense for as to why when I use a pulldown resistor I finally get a reading of some sort, and nothing with a pull-up. I’m gonna open up my unit for the 2828171 time to confirm that my jumper pins are in the right place, but at this point I am certain they are.

I know that the Hall effect sensor (58x Gm) acts as an open collector. Maybe the solution is for the ecu to not give out 5v from that crank sensor pin, but there is no reason for it to do so to my knowledge. Back to square 1.

On side note, I noticed I was getting readings of some sort when I pulled the signal down using a 1k resistor. But it was inconsistent and most the tooth signals weren’t high enough to be registered by the ecu (viewing via tooth logger). No filtering settings are in use at the moment.

Thank you all for your time and help. I’ll get this thing on the road sooner or later.

I'm having fun in multiplayer mode! I can observe […]

Hello, I know this thread is little bit older, but[…]

Both crank and cam inputs have optional pull-ups w[…]

Yes aux io is 0-1024 , there is no scaling or form[…]

Still can't find what you're looking for?