Due to the high voltages involved in secondary ignition systems,
it is not possible to make measurements by direct connection. Attempting
to make a direct connection will almost certainly damage the measuring
instrument. The TA397 is a capacitive pickup that simply connects around
the insulation of an ignition circuit component such as a plug wire.
This avoids the need for direct connection.
The TA397 comes with a shielded 1.8 m (6 foot) lead. It is suitable for
use with conventional ignition systems and most HEI and DIS systems.
Our library of Automotive Waveforms contains example waveforms captured
using a PicoScope automotive oscilloscope and the TA398 or the MI074 BNC version.
This lead is fitted with a PicoBNC+ interface, allowing it to be recognised by
the software for auto-configuration. The lead requires a PicoScope featuring
the PicoBNC+ such as the 4225A or 4425A.
The PICO-MI074 is a capacitive pickup that simply connects around the insulation of an
ignition circuit component such as a plug wire. This avoids the need for direct connection.
The PICO-MI074 comes with a shielded 1.8 m (6 foot) lead. It is suitable for use with
conventional ignition systems and most HEI and DIS systems. Our library of
contains example waveforms captured using a PicoScope automotive oscilloscope and the PICO-MI074.
How to use the PICO-MI074 Secondary Ignition Pickup
Safety precautions before use:
Keep the lead away from pulleys and other moving parts
Keep the lead away from heat
Never let the pickup come in direct connection with primary or secondary
voltage (otherwise the PicoScope may be damaged)
Always use the ground clip
Do not let the metal portion of the pickup contact a ground
Connecting the PICO-MI074:
1. Connect the PICO-MI074 to the automotive oscilloscope first
2. Connect the ground clip to a good ground on the vehicle and check before attaching the clip to a high voltage lead.
3. Clip the pickup clamp around the insulation of a secondary coil HT lead or plug wire. Never connect directly!
Standard Ignition: clip the pickup around the coil wire (or one plug wire at a time)
Integrated coil: clip the pickup around the central location on the distributor cap
DIS: clip the pickup around one plug wire at a time
While HT leads would appear to be components from the past, the secondary ignition pickup lead is far
from redundant. We have relied on these devices to obtain critical secondary ignition information for years,
assisting with diagnosis of misfires and emission failures.
On older vehicles, you can use a PICO-MI074 to monitor the ignition coil output before the distributor which yields a sequential,
comparitive view of all cylinders in firing order. Identify cylinders by connecting another scope channel to a cylinder-specific
signal to (e.g. an injector or to the CAM sensor) or use another PICO-MI074 on a plug wire. Trigger using that secondary channel.
COP coils are being introduced in many new vehicles. If you wish to conduct hands-free testing of secondary
ignition, an inductive COP proble is difficult to use. We suggest using the PICO-MI074 with our
PICO-TA037 for hands-free intermittent misfire
detection under road-test conditions. These leads allow you to monitor secondary
ignition events, so revealing the activity in each cylinder under true operating conditions.
Typical examples of use:
Confirmation of secondary ignition events
Can be applied to a variety of HT ignition systems, conventional, wasted spark, COP and cartridge-style ignition.
Hands-free misfire detection (unlike the COP/Signal probe)
HT integrity tests
Confirmation of coil on plug serviceability under load