Electrical Connectors - Assist Lever - Brute Force Not Required
Electrical Connectors - Brute Force Not Required.
One of the challenges when working with a multitude of electrical connectors, is that of disengaging a connector from its mating connector or electrical socket. I receive requests for "how to's" related to access and service of connectors. If a minute or two here saves another technician some time by not causing damage, that is the whole point.
While it might seem simple enough given good visible access to a connector, some connectors are buried and barely accessible by hand, let alone visually. Tugging on a wiring harness to improve access, may result in inducing other electrical faults, so should be avoided if at all possible.
For technicians encountering any new connector design for the first time, it is worth visiting service information to reduce the possibility of inflicting damage to the connector.
Sometimes, a mirror or a phone camera can be useful, but the number of damaged connectors statistically reported clearly indicates that learning how the various connector mating components are retained, released, disengaged and re-installed is worthy of taking a two minute tour.
It comes as no great surprise that brute force will readily overcome most any retention method, but given that poor terminal connections will most likely result due to instability or possibly a lack of retention of the connector to its mate. So, we will briefly explore a connector design, that has apparently been a bit of a challenge to some who tend to use brawn rather than brains.
Lever assisted connectors have been widely adopted at some component connectors such as Instrument Panel Cluster (IPC) and air bag Sensing and Diagnostic Module (SDM) connectors. Since these appear to be on the list of often damaged connectors, taking an opportunity to visit retention and release mechanisms, may just save someone from causing damage when it can be avoided.
The vehicle of focus for IPC connection will be … GMC Yukon and its sibling family of trucks and utility vehicles using the same IPC connector in various years.
This particular connector uses a red Connector Positive Assurance (CPA) clip at the release to ensure that the connector remains connected to the socket that is soldered to the IPC circuit board.
However, the IPC bezel has a hood that limits visual access enough to make disconnection a bit more challenging for some, especially those of us with "fat" fingers or reduced sensitivity at the finger tips when groping around in the dark.
Figure 1 shows the hood removed from the dash. This will normally not be removed, but was removed to access other components in the area. The lip of the hood over hangs the bezel by approximately one inch.
Figure 2 shows the IPC rotated rearwards once the four fasteners have been removed that retain it to the instrument panel.
Figure 3 shows the maximum position for access with the park brake applied, transmission moved out of park and the electric tilt steering column set at its lowest position.
Visible access is still limited without the aid of a mirror. The first step to disengage the IPC harness connector is to slide the red CPA clip towards the passenger side of the vehicle.
Figure 4 shows an IPC connector complete with the mating connector that is soldered to the IPC circuit board. With the CPA removed, the edge of the latch needs to be depressed to allow the lever assist to rotate up and over the latch. Any stress on the IPC harness will pull the assist lever hard against the edge of the latch. While it is possible to release the latch using a finger, it may require a small amount of additional deflection to release the assist lever, using a small flat bladed pocket screwdriver or similar tool.
Figure 5 shows the assist lever unlatched and rotating to disengage the connector from the IPC connector socket.
Note: Once the assist lever has moved to fully disengage the connector from its mating socket, the lever will be locked in position. This is often where damage results when technicians try to move the assist lever towards the latched position.
Figure 6 shows the IPC connector aligned and indexed with the IPC socket and the "teeth" of the assist lever mechanism engaged correctly in the IPC socket.
Figure 7 depicts why the assist lever is prevented from moving once disconnected from the IPC connector socket. Only when the mating teeth of the connector halves are timed, can the IPC connector be pushed towards its seated position in the IPC socket moving the retainer that locks the assist lever open.
The ramp engages inside the IPC socket, depressing the tangs that lock the lever open. Once the connector is aligned and depressed, the assist lever is released and rotates to the latched position. The CPA clip is then moved to ensure that the connector remains in the latched position.
The video clip shows removal and insertion of an assist lever connector into a GM Sensing and Diagnostic Module. You will note that as the connector is depressed into the SDM connector, the assist lever moves to the latched position. The mating "teeth" of the assist lever mechanisms align the components during installation. Many times, SDM related DTCs have been found to be as a result of missing or unseated CPAs.
Thanks Martin, excellent presentation as usual!
Thanks Ray. Connections might be considered by some to be insignificant in the big scheme of things. However, as you well know, the integrity of connectors and terminations is paramount to the operation operation of critical vehicle systems and should not be overlooked, given the frequency of damage and poor connections that are encountered.
Hi Marty: Thank you for sharing. While this is an issue with new cars, add some age, gunk and grime to a vehicle and it could end (theoretically) up totaling it. Guido
Absolutely Guido, great points. As a result of what feels like the light weighting and smaller construction, it seems that there is some inherent relatively fragility of some of the connectors in use today, if at all abused or otherwise deteriorated. Many connectors and terminals are designed for a relatively low number of disconnection and re-connection cycles, so service procedures and…
Martin. try releasing the main connector to a late model Volt battery in the chassis. It's such a PITA that G.M. even released a bulletin on how to remove it as techs were breaking the lugs off the connector. Add some age and road dirt and the fun begins. Leave it to G.M. to redesign an easy to service connector on earlier Volts to add a very difficult one. Some of the ABS connectors on C/K…
Hi James. I just read that connector info recently. Go figure. The original connector worked just fine. BTW and I may have mentioned it, but the interlock on the current Volt BDU is no longer functional and has been programmed out, so staging the BDU up a step still results in the vehicle "readying up", which might come as a bit of a surprise In this area we have a lot of fine sand and other…
I will not comment on the Volt connectors but on the low voltage connectors I use a blow gun first then I find Champion RX-454 followed with more air blast usually does the trick.
Those "engineering marvel" (better mousetrap) lever-connectors are a nightmare after they are packed with dirt. Need to drag more engineers out of their caves to see these things when they are 10-15 years old. I know, I know, "they are supposed to buy a new car every three years" - LOL