Triggering a PICO recording with a scan tool
Posted to Technical Tips Forum on 8/9/2015
22 Replies
The other day, I had a 2015 F150 3.5L GTDI with a complaint
of a CEL. It was setting the following DTCs:
P0365:00-28- (PCM) - (CMP) Sensor B Circuit (Bank 1)
P0369:00-28- (PCM) - (CMP) Sensor B Circuit Intermittent
(Bank 1)
After clearing the DTCs, I found it quite difficult to get
the DTCs to return. I was finally able to figure out that if
I allowed the engine to idle long enough, the CMP1_EXH Fault
PID would randomly read "Yes":
2015 Ford F-150 Platinum, ECM/Inputs/Outputs Scan Data
Figuring out the cause wasn't that hard. Another tech
suggested I swap the Intake and Exhaust CMP sensors and see
if the fault followed (fortunately, the sensors are the
same). The fault did follow the sensor:
2015 Ford F-150 Platinum, ECM/Inputs/Outputs Scan Data
A scope wasn't needed to diagnose this, but I still wanted
to get a waveform of the fault just to see electrically what
was going on. The problem with that was the engine might
have to idle for up to 2 hours before it would happen. I had
IDS set up to "Beep" and trigger a recording when the
CMP1_EXH Fault PID changed to "Yes". My next goal was figure
out someway to trigger a scope recording at the same time.
To do that, I connected an extra channel on the scope to the
computer audio circuit using a line in cord plugged into the
headphone jack. I then set up a Single trigger on that
channel with trigger placed about midway in the time base.
Now, when IDS triggered the recording and "Beeped", the
voltage on the audio circuit would trigger, allow the
waveform to fill the buffer, and stop the scope. I was now
able to walk off and do something else.
Here's what I found:
2015 Ford F-150 Platinum, ECM/Inputs/Outputs Waveform
Here it is zoomed in:
2015 Ford F-150 Platinum, ECM/Inputs/Outputs Waveform
At first glance, those spikes on channel B look like
ignition, but it's not.
On a side note, I used one computer for IDS and another
computer for PICO. Here's a good post explaining why:
http://members.iatn.net/forums/read/msg.aspx?f=forum8&m=153633&fv=3&page=1
Robby from Alabama
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