86 951 problems please help... gauge cluster, headlights, turbo
04-25-2011, 02:13 AM
#61
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all right i received the oscope today. I hooked it up today, but don't have much experience with them. I had the positive probe on the signal wire (middle pin) and the other on the ground pin. The only way I was able to pickup any "signal" was going to the finest setting (can't remember the mV reading, but it was pretty small). I was able to pick up a pretty messy square wave that didn't change at all (frequency or amplitude) with the car in first gear or in neutral (didn't test beyond that). Is there something I'm missing here or is this the sign saying it is bad? What "voltage" should the o-scope be set on to see this? Just want to be sure I'm testing it correctly before coming to the final conclusion of the failed sensor. Any help, suggestions, or ideas with this would be a huge help. thanks.
Last edited by 951rook; 04-25-2011 at 03:00 AM.
04-25-2011, 08:30 PM
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The signal rises in amplitude with RPM. At idle, it is the weakest, around 2V. If you set the Y1 to 1V and Y2 to x1, you will get one volt per division IF you are using a 1 to 1 probe.
The large square wave is more then likely your coil transmitting into the scope. It should change with RPM.
The large square wave is more then likely your coil transmitting into the scope. It should change with RPM.
Last edited by Bri Bro; 04-26-2011 at 12:02 AM. Reason: saving bandwidth
04-25-2011, 11:32 PM
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Are you referring to the speedometer sensor on the transaxle, or the speed an reference sensors on the back of the engine near the firewall. We are trying to find if the speedometer sensor on the transaxle is fault or not.
04-26-2011, 12:04 AM
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Long day and yes, wrong sensor. I would expect a 12V pulsed signal since it has 12VDC power going to it. I will have the car on the lift tomorrow and take a look at it. I do believe a easy place to look at that signal is at the cruise control module.
Last edited by Bri Bro; 04-26-2011 at 08:36 AM.
04-26-2011, 12:57 AM
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Those seem to be where the oil cooler loop was once installed, either it was originally a cooled car that had the loop damaged and removed, or maybe a factory block off? Not sure with the 86's when they were standard. The cooler became an option from 87 onward.
04-26-2011, 11:43 PM
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Test point for speedo pulse test. Pin 1 upper plug on cruise control (Red/White) Turn ignition on, jumps to 8 volts. Rotate back tire in neutral and get about two ground pulse per turn of the wheel. NO noise, no square wave just a clean signal.
Sounds like your Speedo sender is shot.
Sounds like your Speedo sender is shot.
Last edited by Bri Bro; 04-27-2011 at 07:58 PM.
05-14-2011, 02:24 PM
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can anyone help me take my car back to the stock boost configuration. pics will help. I have an indash mbc t'd off at the klr. let me know if you need any further information
