No pulse from injectors when cranking

Jerry is 100% right that it's much easier to just replace the sensor. And that (most good) oscilloscopes are expensive, and lastly that learning how to use them isn't necessarily the easiest thing in the world.

BUT SINCE YOU ASKED..... I found a cheap ($30) oscilloscope on amazon and it works great for this sort of thing. I posted an article in our how-to section for testing the camshaft position sensor (which I am too lazy to find & link), and I have a video of the process as well...aside from the connector itself and the specific pinouts for your year, testing the cam sensor is identical to testing the crank sensor. And also obligatory comment about how the cam & crank work together to determine timing & ignition advance, and you can't tell if they're working together with a single channel scope. But knowing how to tell if they are "in phase" enough further underscores Jerry's comment above.


Great troubleshooting video....
Thanks for sharing with the forum members.
 
  • Like
Reactions: hear
lol it's like the 4th time I've posted it for various reasons, you must have me blocked. ;) I'm working on a series for testing all/most of our sensors. New job is getting in the way though.

There's another scope that is multi channel for about $150 on amazon. It's tempting, but I'm not done being impressed with this little guy just yet.
Yeah I'm tempted by the more expensive scopes too, I miss not having one as I spent too many years using them to not have access to one now. I actually built a 5" oscilloscope from a Heathkit kit in 1964 or 1965 when I was taking electronics in high school. It worked great but it was frigging stolen during a loan to a guy I worked with after I got out of the military. I should have made him pay for it but was too nice of a guy way back then lol. Then onto a whole bunch of high-end HP oscilloscopes in college, the Air Force, and then the mainframe computer industry. Dang I loved those things and really miss not having one. I'll probably just go for the $30 version but damn some of the others aren't that much more expensive so they are extremely tempting. At this point in my retired life I'm having trouble figuring out what I'd do with it but.... :ROFLMAO:
 
Jerry is 100% right that it's much easier to just replace the sensor. And that (most good) oscilloscopes are expensive, and lastly that learning how to use them isn't necessarily the easiest thing in the world.

BUT SINCE YOU ASKED..... I found a cheap ($30) oscilloscope on amazon and it works great for this sort of thing. I posted an article in our how-to section for testing the camshaft position sensor (which I am too lazy to find & link), and I have a video of the process as well...aside from the connector itself and the specific pinouts for your year, testing the cam sensor is identical to testing the crank sensor. And also obligatory comment about how the cam & crank work together to determine timing & ignition advance, and you can't tell if they're working together with a single channel scope. But knowing how to tell if they are "in phase" enough further underscores Jerry's comment above.


You lost me at the K&N sticker 🤣
 
Jerry is 100% right that it's much easier to just replace the sensor. And that (most good) oscilloscopes are expensive, and lastly that learning how to use them isn't necessarily the easiest thing in the world.

BUT SINCE YOU ASKED..... I found a cheap ($30) oscilloscope on amazon and it works great for this sort of thing. I posted an article in our how-to section for testing the camshaft position sensor (which I am too lazy to find & link), and I have a video of the process as well...aside from the connector itself and the specific pinouts for your year, testing the cam sensor is identical to testing the crank sensor. And also obligatory comment about how the cam & crank work together to determine timing & ignition advance, and you can't tell if they're working together with a single channel scope. But knowing how to tell if they are "in phase" enough further underscores Jerry's comment above.


Great guide, thanks! I've ordered the same oscilloscope so hopefully I can test the cam and crank sensor to make sure this is working.


In the meantime I did some extra testing on the injectors. When I initially tested them I used one of those led lights with a short and long leg, and it lit up nicely when directly connected to my battery. I attached that led light to orange-dark green wire to see if it would stay lit when cranking, which it didn't. It only lit up once shortly when turning the key to the "ON" position. Now, I've tested this again but with a voltage meter. I measure the same short initial impulse when I turn the key on, but when cranking I get a fast fluctuating voltage, changing almost too fast to see how high or low it goes. It does definetely go below 10V, but I don't know if it goes to 7V and back or if it is on its way to 0V before receiving a different impulse shooting it to 10-12V again. Is this normal or should this be a constant, uninterrupted 12ish volt supply?
 
Great guide, thanks! I've ordered the same oscilloscope so hopefully I can test the cam and crank sensor to make sure this is working.


In the meantime I did some extra testing on the injectors. When I initially tested them I used one of those led lights with a short and long leg, and it lit up nicely when directly connected to my battery. I attached that led light to orange-dark green wire to see if it would stay lit when cranking, which it didn't. It only lit up once shortly when turning the key to the "ON" position. Now, I've tested this again but with a voltage meter. I measure the same short initial impulse when I turn the key on, but when cranking I get a fast fluctuating voltage, changing almost too fast to see how high or low it goes. It does definetely go below 10V, but I don't know if it goes to 7V and back or if it is on its way to 0V before receiving a different impulse shooting it to 10-12V again. Is this normal or should this be a constant, uninterrupted 12ish volt supply?

The injectors are low side controlled, the ASD supplies the 12v to the injectors, the PCM switches the ground on and off as needed based upon crank sensor pulse input.

If you did not have a valid crank sensor input the ASD would not remain latched, which you have already verified as working.

If you have voltage at the injectors and it is being switched on and off then the problem is elsewhere.
 
Jerry is 100% right that it's much easier to just replace the sensor. And that (most good) oscilloscopes are expensive, and lastly that learning how to use them isn't necessarily the easiest thing in the world.

BUT SINCE YOU ASKED..... I found a cheap ($30) oscilloscope on amazon and it works great for this sort of thing. I posted an article in our how-to section for testing the camshaft position sensor (which I am too lazy to find & link), and I have a video of the process as well...aside from the connector itself and the specific pinouts for your year, testing the cam sensor is identical to testing the crank sensor. And also obligatory comment about how the cam & crank work together to determine timing & ignition advance, and you can't tell if they're working together with a single channel scope. But knowing how to tell if they are "in phase" enough further underscores Jerry's comment above.


I've bought the same(ish) oscilloscope as in your video, apart from the color, but I am struggling with mine. I entered the same settings (from what I can tell) as you had on your oscilloscope (5V, 20ms, trigger auto, DC) but I when I crank my engine nothing changes on the screen... I connected everything as you explained, red on signal wire and black on battery ground. Any idea on what I might be doing wrong? Or did you do something extra to callibrate it because the "manual", if you can call it that, is almost non-existent for a novice like me to callibrate it correctly...
IMG_6060.jpg


 
Verify that you have 12 volts at the orange/green wire at the injector connector. if you don't check fuse 21 in the PDC. The use of a noid light to establish injector pulse is helpful.
If you have access to a scan tool that reads live data, check and see if you have cam and crank RPM while attempting to start the vehicle.
One thing you failed to mention, is there a CEL on and is there any codes in the system.
 
I've bought the same(ish) oscilloscope as in your video, apart from the color, but I am struggling with mine. I entered the same settings (from what I can tell) as you had on your oscilloscope (5V, 20ms, trigger auto, DC) but I when I crank my engine nothing changes on the screen... I connected everything as you explained, red on signal wire and black on battery ground. Any idea on what I might be doing wrong? Or did you do something extra to callibrate it because the "manual", if you can call it that, is almost non-existent for a novice like me to callibrate it correctly...
View attachment 408259

View attachment 408258

You bought the dark gray one?? That one only works in Europe where they run on 50hz.


Just kidding. Yes, the manual is a joke. I struggled with the calibration because the instructions barely made sense. Re-reading mine, I believe you hold down the v/div button to enter calibration mode. Then adjust the voltage through its entire set of ranges. Then switch the coupling mode and cycle through the voltages…repeat for all coupling modes. I remember doing it several times because something about it didn’t feel right.



Even then it wasn’t perfectly calibrated. I tested it against my 5V supply and adjusted the voltage knob until it was at the major tick on the y axis. In DC mode.

Then I connected to the sensor and when I cranked the engine the numbers fit the RPMs so I felt good about it.
 
Verify that you have 12 volts at the orange/green wire at the injector connector. if you don't check fuse 21 in the PDC. The use of a noid light to establish injector pulse is helpful.
If you have access to a scan tool that reads live data, check and see if you have cam and crank RPM while attempting to start the vehicle.
One thing you failed to mention, is there a CEL on and is there any codes in the system.

No CEL and no codes, tested with OBDII reader and the key trick to check gauges and display codes. Fuse 21 looks good.
You bought the dark gray one?? That one only works in Europe where they run on 50hz.


Just kidding. Yes, the manual is a joke. I struggled with the calibration because the instructions barely made sense. Re-reading mine, I believe you hold down the v/div button to enter calibration mode. Then adjust the voltage through its entire set of ranges. Then switch the coupling mode and cycle through the voltages…repeat for all coupling modes. I remember doing it several times because something about it didn’t feel right.



Even then it wasn’t perfectly calibrated. I tested it against my 5V supply and adjusted the voltage knob until it was at the major tick on the y axis. In DC mode.

Then I connected to the sensor and when I cranked the engine the numbers fit the RPMs so I felt good about it.

Tried it multiple times, but my oscilloscope does not go into callibration mode so I think it's faulty and will send it back.

I will order a new one but first will replace my coil. I had already checked my spark with a test tool that you put inbetween the distributor and the sparkplugs, and the built-in light flashed on all of them so they were receiving spark (I thought). I also tried to crank it 5+ times for more than 5sec to see if the sparkplugs would be wet aka fuel but no spark, but they were as dry as the desert making me think the fuel was the culprit. Today out of desperation I tested the coil again with another tool (see video) and according to the instructions the coil should have at a gap of 1cm as it is a nice, straight blue spark. Mine is red and weak, which would indicate a bad coil. So before I continue on the oscilloscope learning trip I'm going to replace my coil and see if that might have been the problem.
 
  • Like
Reactions: hear