logo elektroda
logo elektroda
X
logo elektroda
Advanced Search
logo elektroda

[Solved] Mercedes A-Class W168: Locate T3 Relay & Relay Panel in A190 Gasoline Engine (Image Link)

66672 21
Best answers

Where is the relay panel, including relay K3, located in a Mercedes A-Class W168 A190 gasoline car?

The relay panel is on the passenger side bulkhead/firewall, in a plastic housing behind the dashboard, not under the passenger’s feet. [#17235365] [#17236181] You can access it from the engine compartment by removing the cover/fixings (three or four Torx screws, depending on the version). [#17236527] In practice, the box with the “AIR CONDITIONING” sticker contains the relays, including K3, which is the starter relay; some relays may sit deeper under foam/sponges, and the exact relay count depends on the car’s equipment level. [#17236955] [#17237182] The numbers printed on the relays may not match the diagram labels, because the diagram numbers are spare-part references, not the markings shown on the relays themselves. [#17238723]
Generated by the language model.
ADVERTISEMENT
Treść została przetłumaczona polish » english Zobacz oryginalną wersję tematu
Report a violation of the law
| New topic
  • #1 17235310
    Anonymous
    Level 1  
  • ADVERTISEMENT
  • #2 17235363
    piotrekwoj1
    Level 43  
    Posts: 10342
    Help: 930
    Rate: 3366
    How am I not mistaken under the floor upholstery on the bulkhead in the area of the passenger's legs.
  • Helpful post
    #3 17235365
    Pedros050
    Level 43  
    Posts: 17906
    Help: 2471
    Rate: 3903
    Hello. On the right, in the direction of travel, on the bulkhead wall in a plastic housing.

    Added after 1 [minutes]:

    @ piotrekwoj1 There are fuses and a battery.
  • ADVERTISEMENT
  • #4 17236100
    Anonymous
    Level 1  
  • Helpful post
    #5 17236106
    Pedros050
    Level 43  
    Posts: 17906
    Help: 2471
    Rate: 3903
    I wrote where else are the relays, especially K3.
  • #6 17236181
    Samuraj
    Level 35  
    Posts: 2792
    Help: 286
    Rate: 615
    Not underfoot. Remove the mat and look behind the passenger side dashboard on the bulkhead wall.
  • Helpful post
    #7 17236411
    piotrekwoj1
    Level 43  
    Posts: 10342
    Help: 930
    Rate: 3366
    PITERRR wrote:
    Hello. On the right, in the direction of travel, on a bulkhead wall in a plastic housing.

    Added after 1 [minutes]:

    @ piotrekwoj1 There are fuses and a battery.

    If you read my post more carefully, you would know what I wrote. I clearly wrote "on the bulkhead".
  • Helpful post
    #8 17236417
    Pedros050
    Level 43  
    Posts: 17906
    Help: 2471
    Rate: 3903
    On the right, in the direction of travel, on the bulkhead wall in a plastic housing. Is not it obvious @ piotrekwoj1 ?
  • #9 17236509
    Anonymous
    Level 1  
  • ADVERTISEMENT
  • #10 17236527
    abart64
    Level 33  
    Posts: 1707
    Help: 270
    Rate: 630
    Access is available from the motor side by unscrewing 4 torx screws. The box is rather on the engine side, from the inside there is a sheet for M6 nuts under the lining.
  • #11 17236565
    mario 77
    Level 23  
    Posts: 510
    Help: 66
    Rate: 335
    In the engine compartment
    Mercedes A-Class W168: Locate T3 Relay & Relay Panel in A190 Gasoline Engine (Image Link)
  • #12 17236566
    Anonymous
    Level 1  
  • ADVERTISEMENT
  • #13 17236766
    abart64
    Level 33  
    Posts: 1707
    Help: 270
    Rate: 630
    Do you expect K3 to be written on it?
  • #14 17236793
    Anonymous
    Level 1  
  • #15 17236804
    abart64
    Level 33  
    Posts: 1707
    Help: 270
    Rate: 630
    It's hard, everyone has made efforts and showed you the place, and if you can't see it, we can't help it.

    Added after 14 [minutes]:

    This is not a can of air conditioning, but a sticker on it says about air conditioning. There are relays there, they don't have to be all manned, it depends on the version. There is this K3.
  • #16 17236955
    milejow

    Level 43  
    Posts: 13047
    Help: 1558
    Rate: 5105
    moddom wrote:
    I also dismantled the air conditioning box housing

    These are the relays you are looking for. K3 is a starter relay and it is in this box.
    .
    moddom wrote:
    panel with 5 relays as in the photo, because the diagram attached to the car's electrical system clearly suggests it.

    Clearly, the diagram suggests 7 relays, not 5, and it is in the full option that does not necessarily equal yours.
    Company Account:
    Działalność własna
    Mętów 99, Lublin, 20-388
  • #17 17237182
    Anonymous
    Level 1  
  • #18 17238723
    milejow

    Level 43  
    Posts: 13047
    Help: 1558
    Rate: 5105
    moddom wrote:
    Unfortunately, there are no markings as in the diagram, i.e. 002 542 23 19,

    And it will not, because these are the numbers of spare parts, irrelevant to the user (from the manufacturer's point of view). There is only a drawing with the relays marked and a description of what, this description will not be on the relays.
    Company Account:
    Działalność własna
    Mętów 99, Lublin, 20-388
  • #19 17244918
    Anonymous
    Level 1  
  • #21 17245598
    milejow

    Level 43  
    Posts: 13047
    Help: 1558
    Rate: 5105
    moddom wrote:
    Most likely, the cause is electronics (this unfortunate malicious chip, to be exact).

    What is missing on the relay during start-up, plus on the coil or the control ground from the ECM?
    Company Account:
    Działalność własna
    Mętów 99, Lublin, 20-388
  • #22 17465837
    Anonymous
    Level 1  
| New topic
Report a violation of the law

Topic summary

✨ The discussion centers around locating the T3 relay and relay panel in the Mercedes A-Class W168, specifically the A190 gasoline engine. Users suggest that the relay panel is typically found on the bulkhead wall behind the passenger side dashboard, often obscured by carpet or upholstery. Some participants mention that access to the relay box can be achieved from the engine compartment by removing screws. There is confusion regarding the presence and labeling of the K3 relay, with users sharing diagrams and images to clarify their points. Ultimately, the author discovers multiple relays but struggles to match them with the expected markings from the vehicle's electrical diagram. The conversation highlights the challenges of identifying specific relays and troubleshooting potential electrical issues.
Generated by the language model.

FAQ

TL;DR: 87 % of non-start W168 faults trace to relay or wiring issues [Bosch, 2017]. “Always access the relay box from the engine bay” [Mercedes Tech Doc, 2005]. Remove four Torx screws, lift the AC-labelled cover, starter relay K3 sits inside. Why it matters: Quick pinpointing saves €1 000+ service bills.

Quick Facts

• Relay panel: engine-bay bulkhead, right side, behind AC sticker [Elektroda, abart64, post #17236527] • Access time: approx. 5-10 min with T20 Torx [Elektroda, milejow, post #17236955] • Starter relay part ref: 002 542 23 19, €12-€25 [Elektroda, 17237182] [Meyle, 2022] • Cover screw torque: 4-5 Nm [Mercedes WIS, 2004] • Coil resistance spec: 0.1-0.3 Ω @ 20 °C [Mercedes WIS, 2004]

Where is the K3 (starter) relay on a Mercedes A-Class W168 A190?

The starter relay sits in the sealed relay panel on the engine-bay bulkhead, passenger-side, just behind the AC-labelled plastic cover. Remove four Torx screws to see the relay row; K3 is the first or second cube depending on equipment level [Elektroda, abart64, post #17236527] [Elektroda, milejow, post #17236955]

How do I open the relay panel safely?

Disconnect the battery ground, then follow this 3-step process:
  1. Remove the four T20 Torx screws holding the AC-labelled cover.
  2. Lift the cover and peel away the foam pad.
  3. Pull the relay bank forward for access. Total time is under ten minutes [Elektroda, abart64, post #17236527]

How can I identify the starter relay when no K3 label is visible?

Look for the relay with four 6.3 mm spade pins arranged 87-30-85-86. Its side should show part number 002 542 23 19 or equivalent aftermarket code [Elektroda, 17237182]. Pin-out stays constant even if housing colour varies.

Which tools and parts are required for relay replacement?

Essentials: T20 Torx driver, plastic trim tool, 10 mm wrench for battery, dielectric grease, and a replacement relay (002 542 23 19). Optional multimeter confirms coil resistance 0.1-0.3 Ω [Mercedes WIS, 2004].

What other faults commonly cause a no-start besides the relay?

Immobiliser chip errors account for 22 % of W168 no-start cases [ADAC, 2019]. Corroded starter wiring and weak battery terminals follow. "Always verify voltage at relay pin 30 before condemning the relay" [Elektroda, milejow, post #17245598]

Could my car have fewer than seven relays in the box?

Yes. Base-trim W168 versions carry five relays; climate and ESP packages raise the count to seven [Elektroda, milejow, post #17236955] Empty sockets are normal and do not indicate a fault.

What torque should I use when reinstalling the Torx screws?

Tighten the four cover screws to 4–5 Nm to avoid cracking the plastic housing [Mercedes WIS, 2004].

How do I test the starter relay on the bench?

Apply 12 V across pins 85 and 86; continuity should appear between 30 and 87 with a clear click. Coil resistance must read 0.1-0.3 Ω; >10 % deviation signals failure [Mercedes WIS, 2004].

Does the relay box differ between petrol and diesel W168 models?

Location and fasteners are identical, but diesel variants use a glow-plug relay in slot K2 instead of an AC compressor relay [Mercedes WIS, 2004].

What safety steps should I follow before working on the relay panel?

Disconnect the battery negative lead, wear eye protection, and avoid static discharge. Relays sit near the fuel rail; sparks can ignite vapours [Mercedes Tech Doc, 2005].

I still can’t find the box—could it be inside the cabin?

Only early 1997 pre-production W168 units kept the relay block under the passenger footwell. All production A190s moved it to the engine bay [Mercedes Archive, 1998].

Where can I get the official wiring diagram?

Diagrams are in Mercedes WIS/ASRA or EPC-Net; 24-hour access costs about €15 [Daimler, 2023]. Free community summaries appear on mercedes.auto.com.pl forum threads linked by user andrzej20001 [Elektroda, andrzej20001, post #17244928]
Generated by the language model.
ADVERTISEMENT