Electrical Connector and Service Part 2
Electrical Connector and Service Part 2.
Electrical Connector and Service was the topic of focus here: diag.net/msg/m4gczf77pb…and prompted some questions and follow up, hence Part 2 was created to demonstrate some assistance for technicians by tying the use of information, tools and processes together in regard to GM vehicle applications.
The focus is how to locate and utilize service information to inspect and service an Ethernet Bus wiring termination concern on a … GMC Terrain. The customer concern described an inability to connect and access various features that are "beamed" into the vehicle via antennas.
The layout of the major components on this Ethernet-based with the Radio as the Bus Master Controller and the Telematics Communication Interface Control Module (TCICM) serving as a modem. These components also have various antennas built-in or connected to them.
Note: When diagnosing customer concerns, always explore all system functions. In other words, while the customer may relate only a single fault, there may be faults in the system for options that are not used. When dealing with any signals that enter the vehicle via the various antennas, check each type of signal.
The issue identified a DTC that related to a failure in the circuit that comprises the A11 Radio and the K73 TCICM (Telematics) module and related wiring. The Bus Master (radio) performed circuit testing when the failure occurred and identified that the Telematics module (end point module) was not communicating.
Armed with a wiring schematic, we will explore the circuit at the Telematics connector. In a previous article, the A11 radio Ethernet connector service procedure and tools were identified and described. For this post, the Telematics X1 connector which receives Ethernet communication from the A11 X6 connector, will be identified and addressed via service information and photographic representation.
Figure 1 show a view of the black X1 connector at the rear of the Telematics module, adjacent to the antenna coaxial cables.
The two Ethernet Bus 4 circuits of focus are housed in this connector in cavities 28 (7211 GY/WH) and 29 (7210 GY) respectively, as on the wiring schematic. Hovering over each circuit with the CGM viewer plug-in, highlights each conductor path in red (not shown) and identifies Ethernet Bus 4+ and Bus 4-.
Figure 2 shows the N/A (white) Connector Positive Assurance clip being worked gently to the unlocked position.
Figure 3 shows the connector as being manufactured by Molex from the MCD abbreviation on the connector body.
After building a 2019 GMC Terrain in GM Service Information, there are a few paths that can lead to a document that provides information about the connector and terminations, plus service procedures. It depends on the technician's knowledge and expertise using SI and his/her preferred search methods.
Since the component code for Telematics was known to be K73, keyword searching "Master" to locate the "Master Electrical Component List that resides within "Wiring Systems and Power Management could be used. However there is a hyperlink directly from the keyword search window to the "Master Electrical Component List" which provides a more direct path to locate information about connectors and terminals, plus harness routing.
Using "K73" for the Telematics component code, searched the list and provided results about the connector and terminations.
The Infotainment system RPO code options had already been obtained prior to selecting the correct connector X1 for the end view document.
The locator view information identifies that the K73 module is located behind the instrument panel. It is found directly behind the radio controls as shown in Figure 4.
The K56 Serial Data Gateway Module (SDGM) aka Central Gateway Module (CGM) also is located in this area clipped into the dash just above the K73 Telematics module. The top of the latch and Telematics module are barely visible at the bottom of Figure 5 below the arrow.
Selecting the X1 connector, nets the connector end view and information about the OEM connector, service connector, the type of harness and a description of the connector in Document ID # 4932885.
A table beneath the connector part information identifies the type of terminals fitted, in this case Type I and II (Roman Numerals)
The terminal Type II in the table that references terminals 28 and 29, identifies the that terminated leads are available as shown in Figure 6. From the terminal identification list beneath the table in SI, terminals 28 and 29 are Type II
Terminated leads when available, are available in quantities of 5 per package, with the Type II terminated leads as shown in Figure 7.
Scrolling down the document, revealed that terminals 28 and 29 are the twisted pair Ethernet Bus # 4 wires. These have grey insulation with a white strip and plain grey insulation respectively and are located as shown in the circle in Figure 8.
Okay, for what it is worth, many male technicians have some form of colour blindness, so the importance of identifying the actual terminal pin location in a connector cannot be over emphasized. Know the location and having good colour recognition allows the technician to accurately pinpoint the location of the terminals to be inspected and/or serviced.
Figure 9 shows an X1 connector with Terminal Positive Assurance (TPA) "staged" to allow removal and insertion of terminated leads.
Figure 10 shows the EL- 38125-58 terminal release tool inserted into the terminal release canal, with terminals 28 and 29 removed from the connector body. Repair is by terminated lead.
EL-35616-58 is used to probe the terminals, as identified in the table.
Figure 11 shows the relative length of the terminal in this connector.
or for the metrically challenged......Figure 12
Figure 13 shows that to release the terminals, EL-38125-58 is used, but first the Terminal Positive Assurance (TPA) must be "staged" as shown using a small screwdriver, until a "click" is heard and felt. EL-35616-58 probe is used to verify terminal pin tension.
Figure 14 shows that with all terminals removed, the connector body can be completely disassembled with some care using a pocket screwdriver, with the component parts all visible after careful disassembly.
Martin, thank you for the series! I think you are the first on this site to mention colour blindness. I‘d be grateful if you could provide some insight into this topic. Are people with colour blindness able to be just as successful in this industry, do they have to come up with workarounds while working with wiring and wiring diagrams? Is this issue even recognized by manufacturers?
Thanks Dmitry. I personally am not colour blind and do not know much about colour blindness. However, male colour blindness is known to affect many technicians and there are apparently different degrees of the condition. I do not know how female technicians might be affected in contrast, so perhaps we have something to learn in this respect. Maybe those so affected might chime in and provide us…
Martin, sorry for taking so long to answer -- I was on a wilderness trip. Thank you for the tutorial on how to read connectors for the colour blind, I think it is very helpful. If you are interested in how articles look like for the affected people, the Chrome Daltonize plug-in may be convenient: chrome.google.com/webstore/detai… Just select which colour blindness…
Thanks Dmitriy. I will take a look at the link, sounds interesting. There are many things that we take for granted, that others many find challenging, so there is value in discussing these conditions to better understand and apply solutions! Here is another link that compares various stages of colour blindness. colourblindawareness.org/colour-blindne…
The owner is color blind and used to run circles around anyone 35yrs AGO.HE started at a union 76 gas station in 1969,moved on to firestone and was master tech of the year for 15 years RUNNING.TOTAL color BLIND.HE always looks for terminal id numbers and I never seen him look twice at any wiring diagram or SI.HE has a degree in engineering…
Hi Lance. It is almost an "advantage" to be colour blind when learning about circuits and terminations, since identifying the terminal by location is the most accurate method, unless it was assembled incorrectly. That is when not being colour blind kicks in as a benefit. E.G. knowing and being able to visually recognize that terminal 14 in connector X1 should be a yellow insulated conductor…
Hi Marty: "Metrically challenged"? Touche! Good information and thank you for sharing. As a quick aside. Back in 2000, guys used to blow off the SI parts of the training classes. I tried telling them that this is the most important part of the class but most never thought so. If you can't find it,... Guido
LOL Guido! Men in general, do seem to be rather more challenged than our female counterparts when making the effort to read instructions!