Hyundai r130 rpm sensor

I'd go with a 1 amp ATO fuse to supply the power—gives you some protection. What I'm seeing is that there should be 20-25 volts going in, and it ramps up close to 28 volts once the alternator kicks in.

I was planning to hook up a fused wire temporarily from the battery direct to pin 7 of the CPU.

Not really an update on the RPM situation, and I probably need to change this thread's title. But I did figure something out. The RPM and temperature gauges are both not working on the cluster. I connected an adjustable resistor to the sensor wire and found I could control the temperature reading on the monitor. The sender itself is only 6 months old and came from Cummins. A replacement is on the way now. That makes me think the RPM sensor might be the problem. Once the weather clears up, I'm planning to go back and test that sensor from scratch.

That wouldn't be the first time I've run into a faulty new sensor. Just because it's new doesn't mean it actually works.

I checked the RPM sender and found I'm not getting 5v with the engine running, plus the resistance value is way off. I've got a new sensor on the way and I'm going to verify it has the correct values before I install it. I'm basically starting over from scratch with new sensors and not assuming anything at this point. I also ordered a new coolant level sensor since that one never worked either.

I've run into a bunch of bad diodes from Caterpillar that were still factory sealed. Tested them right through the packaging with a multimeter using sharp probes, and the head mechanic confirmed they were all defective. It happens more often than you'd think.

So I went ahead and swapped in that new tach sensor, and sure enough, I'm getting engine speed now. Turns out the original one wasn't outputting properly after all. Got a new temp sensor coming today—hopefully I made the same mistake there and it'll fix that issue too.

Thanks for sharing the fix.