Alternator 12V 120A High Output
w/harness - suits 1PZ, 1HZ, 1HDT, 1HDFT, 1HDFTE
DXA433HO
| Article number: | 28420-17011 |
| Availability: | Out of stock |
This solenoid is responsible for connecting the LH and RH batteries together in series to provide 24V while cranking the starter motor, and then returning the batteries to a parallel connection when the starter is not cranking.
The starter motor is fully 24V in JDM sourced HDJ81s.
The 24V switch-over process is controlled by a Timer ECU that coordinates the switching process from 12V to 24V for starting (cranking) and isolating the left side battery from the rest of the vehicle and charging system. The Timer ECU itself is not prone to failure, and is located inside the left front kick panel (on RHD models).
When this solenoid is wearing out, it can lead to "no crank" situations where only a relay (solenoid) is heard to be clicking.
Other symptoms of a wearing solenoid are poor/weak or absent battery charging of one battery (the left one) or sometimes both batteries.
If you are testing this solenoid, as with any other solenoid, you must look for both current and voltage. Voltage alone does not necessarily provide clues to failure. It is possible to have good voltage readings when the circuit is not loaded, and yet poor current pass through and low voltage when it is loaded. ie: test this under a moderate load to emulate the starter motor's load when evaluating its performance.
Note 1: It is important that both batteries are healthy and in a high state of charge for the starting system to operate correctly. If you are testing the batteries with an inductive tester or a load tester, then the batteries must be disconnected from the vehicle and isolated to get a good reading.
Note 2: Check all battery connections, grounding points, starter solenoid, and series-parallel switching solenoid connections, along with fuses (fuse box) and fusible links (near the battery terminals) for having good, clean, corrosion-free contact points before digging in too far.
Note 3: DO NOT connect any accessories to the Left Hand side battery. During engine cranking, the left hand side battery is connected in series to the RH side battery to provide 24V power for the starter motor. This means that the negative post becomes positive during cranking, and the positive post is goes to 24V.
....DO NOT connect any accessories to the Left Hand side battery.
If you connect a wire to the negative post on the LH battery that connects to a ground - such as through a winch motor or driving lights (this is a common mistake!), then you're going to have some pretty serious electrical problems including a weak or no crank, and a hefty short circuit that could let a substantial amount of smoke out of the wires.
Note 4: Do not connect jumper cables to the LH battery - this is stated on the yellow label and protection cover that is supposed to be over top of the LH battery. This label is often missing...
Caveat: If you are going to connect jumper cables to the LH battery, the connected battery must be isolated from the rest of the vehicle and the connections must be made directly to the terminals of the LH battery only, and not to grounding points at any other location.
You can also connect a jumper battery to the RH battery, but again it is best to only connect to the terminals of the battery, and not the ground.
WARNING: Be careful when making or breaking these connections - small electrical sparks can ignite battery hydrogen gas if it is present and cause a battery explosion (which will spray the surrounding area - and you! - with sulfuric acid).
Toyota pn:
28420-17010
28420-17011
Toyota - Japan
2022 03 29
2842017011
