Description
1. The “Hidden Pair” – Why This Sensor Cannot Be Replaced Alone
On the Hitachi EX1200-5, the transfer case (splitter box) level sensor YA00058748 has a critical design quirk: it comes with a pre-attached harness section that mates to main machine harness. The connector pins are not serviceable separately. If the sensor fails, you must also replace the matching harness sub‑assembly YA00058747 (item 32 in the parts diagram).
| Component | Part Number | Why Both Needed |
|---|---|---|
| Level sensor (probe + short pigtail) | YA00058748 | The sensing element itself – detects low oil level |
| Harness sub‑assembly | YA00058747 | Connects sensor to main harness; pins corrode as a pair |
Attempting to replace only the sensor: The old harness connector has matching corrosion or pin damage. You will connect a new sensor to a bad harness – intermittent warnings or no signal. The system will still fail.
Our solution: We supply both YA00058748 and YA00058747 as a matched set. No guesswork, no repeat repairs.
2. How Corrosion Kills This Sensor – And Why It Spreads to the Harness
The EX1200-5 transfer case sits low on the machine, exposed to water, mud, and salt. The sensor connector is not fully sealed from the factory. Over time, moisture wicks into the pins.
| Stage | Condition | Symptom |
|---|---|---|
| 1 (early) | Light corrosion on sensor pins | Intermittent “low level” warning when machine bounces |
| 2 (moderate) | Corrosion spreads to harness side | Constant warning – even with full oil |
| 3 (advanced) | Pins break or short | ECU reads “level low” – machine may derate or refuse travel |
When you reach stage 2 or 3, the harness pins are already damaged. A new sensor plugged into a corroded harness will not fix the problem. You will chase the warning for weeks.
3. The “Sensor + Harness” Bundle – What You Get
We pre‑assemble the pair before shipping (loose, but tested together). You receive:
| Item | Part Number | Condition | Note |
|---|---|---|---|
| Transfer case level sensor | YA00058748 | Genuine Hitachi, Japan | Includes probe and 30cm pigtail |
| Harness sub‑assembly | YA00058747 | Genuine Hitachi, Japan | About 1.5m length, pre‑terminated |
| Heat shrink tubing | N/A | Included (free) | For sealing the new connection |
| Dielectric grease packet | N/A | Included (free) | For pin protection |
You do not need to buy separately or search for a corroded harness. We provide both.
4. Installation Sequence – Do This Exactly
Because the harness connects to the main machine harness inside the cab or behind the battery box, the job requires some disassembly. Follow these steps:
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Disconnect battery (critical – the level sensor circuit is live with key off on some EX models).
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Trace old harness YA00058747 from sensor back to its main connector.
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Remove old sensor and old harness as one assembly.
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Do not cut wires. Unplug the main connector.
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Install new harness YA00058747 first – route exactly as original (use cable ties).
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Plug new sensor YA00058748 into the new harness.
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Before final tightening, apply dielectric grease to both ends of the connector.
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Use the included heat shrink on any exposed splice points (if field splicing is unavoidable – though we recommend full harness replacement).
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Fill transfer case to correct level (refer to machine manual).
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Reconnect battery and test: turn key on, warning lamp should be OFF. Disconnect sensor – warning should appear. Reconnect – warning off.
Estimated time: 2–3 hours for a skilled technician.
5. What Happens If You Ignore the Warning?
The EX1200-5 transfer case (also called splitter box) distributes power from the engine to the front and rear drive lines. Low oil level, if undetected, leads to:
| Consequence | Repair Cost (est.) | Downtime |
|---|---|---|
| Bearing failure | $8,000–$12,000 | 5–7 days |
| Gear tooth spalling | $15,000–$20,000 | 10–14 days |
| Seized transfer case | $25,000–$35,000 | 2–3 weeks |
The sensor + harness cost is a tiny fraction of that. Replace proactively.
6. Real Case – A Mine That Learned the Hard Way
A coal mine in Kalimantan had an EX1200-5 with an intermittent level warning. Their mechanic replaced only the sensor (YA00058748) with a non‑genuine part. The warning stayed on. He replaced it again. Still on. After three sensors and two weeks of frustration, they called us.
We supplied the genuine sensor plus the harness YA00058747. The old harness had corroded pins inside the main connector – invisible until removed. After replacing both, the warning disappeared. The machine returned to work the next day.
The mine’s maintenance supervisor: “We wasted $900 on sensors and 16 labor hours. The harness cost less than one sensor. Now I know: always change them together.”
7. Technical Specifications – For Your Records
| Parameter | Value |
|---|---|
| Sensor type | Reed switch + float (normally open, closes when level low) |
| Thread size | M18 x 1.5 |
| Harness length | Approx. 1.5m (from sensor to main connector) |
| Connector type | Sumitomo 2‑pin, waterproof (with new seals) |
| Operating voltage | 12V DC (signal to ECU) |
| Genuine part numbers | YA00058748 (sensor), YA00058747 (harness) |
8. Ordering Information – Matched Set Only
We do not sell the sensor alone for EX1200-5. Experience shows that causes repeat failures and customer frustration.
| Item | Detail |
|---|---|
| Compatibility | Hitachi EX1200-5 (also EX1200-3? Check manual – different harness length) |
| MOQ | 1 set (sensor + harness) |
| Lead time | 6–8 working days (stock in Japan → our Guangzhou hub) |
| Packaging | Each in separate Hitachi box, packed together in reinforced carton |
| Payment | T/T, XTransfer, PayPal, Western Union |
| Supply capacity | 50 sets/month (genuine, limited) |
| Warranty | 6 months (manufacturing defects – both components) |
9. Before You Order – Verification
Because EX1200-5 production years had minor harness routing differences, please send:
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Machine serial number (EX1200-5 – xxxxx)
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One photo of the old sensor and the old harness (if accessible)
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Confirmation that the transfer case part number matches (we can cross‑reference)
We will confirm compatibility within 24 hours.
