SOL1099 Solenoid Switch: What It Does

The SOL1099 solenoid switch sits between the battery and the starter motor and does two jobs at once: it throws the drive pinion into mesh and it closes the main contact that feeds the motor. Both actions come from the same plunger, which is why a worn contact shows up as a click with no crank.

Heat and current are the two enemies of a solenoid. The coil sits next to the exhaust side of the engine on many installations, and the contacts carry the full starter current, so both the winding and the disc face degrade faster than the rest of the starting system.

Specification Summary

• 12V nominal coil and contact rating
• Pull-in and hold-in coil in one sealed housing
• Copper contact disc with plated terminal studs
• Direct replacement for the original mounting pattern

Reference Numbers and Cross References

Match the unit by any of the following numbers:

• 2339304007
• 2339304019
• 2339304023
• 2339304015
• 2339304050
• 138763
• SOL1099
• ZM-1-371
• 2339304063
• 2339304068
• 2339304069
• 0331303014
• 0331303046
• 0331303065
• 139075
• E3699

Application Notes

On Bosch Santana installations the solenoid is reached from below or through the wheel arch. Confirm the terminal arrangement (battery stud, motor stud, control terminal) matches the old unit before bolting the new one in place.

Because solenoids are shared across starter families, one switch often covers a long list of vehicles. That breadth is useful for stock, but it makes number checking more important, not less.

How Solenoid Switches Fail

The first failure is usually electrical rather than mechanical: the copper disc erodes until it no longer makes clean contact on both studs.

The second is the winding. A coil that has been cooked by exhaust heat or contaminated by oil will pull in weakly or not at all, and the symptom is a single click from the solenoid with no rotation.

Fault Symptoms

• No crank, but the starter motor spins freely when tested on the bench
• Chattering solenoid during cranking
• Hot start problems after a long run
• Loose or heat-discoloured battery stud on the solenoid
• Control terminal that reads 12 V with the key in START but no action

Testing Before Replacement

Measure the control terminal with the key in START. Battery voltage at the small terminal and no movement means the coil or the earth path is at fault. If the solenoid clicks but the motor does not turn, bridge the two main studs with a heavy test lead: a starter that spins confirms the contacts are the problem.

Before condemning the switch, confirm the battery holds charge and the earth strap is sound. Most 'failed' solenoids that test good on the bench were killed by a poor connection elsewhere.

Installation Notes

Isolate the battery, then photograph the wiring before disassembly. The battery stud and the motor stud are not interchangeable, and reversing them will destroy the new switch on the first start.

After fitting, crank the engine once with the coil lead disconnected to confirm the motor circuit, then reconnect and start normally. Check for a hot terminal or a smell of burning after the first few starts.

Quality Control and Supply

Each production batch is tested for coil resistance, pull-in and drop-out voltage, contact resistance across the main studs and high-pot insulation. Hejian Nuojin Auto Parts Co., Ltd. supplies the switches in neutral packaging with a one-year warranty against manufacturing defects.

Frequently Asked Questions

Why does the starter click but not turn?

A click means the coil is working and the plunger is moving. If the motor does not turn, the main contacts are burned, the motor cable is loose or the starter motor itself has failed.

Should I replace the solenoid when I rebuild the starter?

It is the usual practice. The contacts have the same service life as the brushes, and a rebuilt starter with a worn solenoid comes back with the same complaint.

Do I need to adjust anything after fitting?

No adjustment is needed when the number matches. Check the terminal nuts after the first few starts and confirm the control wire is seated.

How long should a solenoid last?

It depends on starts and heat. A daily-use vehicle typically sees tens of thousands of engagements, and contact wear accelerates on vehicles that crank for long periods.

Installation Method of 12V Bosch Starter Solenoid Switch for Santana

I. Pre-installation Preparation

Safety Precautions and Tools

1. Disconnect the negative terminal of the storage battery (to prevent short circuit).

2. Prepare tools including 10/13/15mm socket wrenches, torque wrench, needle-nose pliers and multimeter.

Removal of the Old Part

1. Unplug the connector of the 50 terminal of the solenoid switch, loosen the nut of the 30 main terminal and remove the power cable, then disconnect the connection between the C terminal and the motor field winding wire.

2. Unscrew the two fixing bolts (usually M6-M8 specification), take off the old solenoid switch, and check whether the shift fork, return spring and iron core are intact.

II. Installation Procedures (for Bosch Original Parts)

Positioning and Pre-installation

1. Align the iron core hook of the new solenoid switch with the starter shift fork to ensure that the shift fork return spring is properly seated, and the dust-proof ring fits closely to the housing to avoid water ingress.

2. Align the mounting holes, insert the fixing bolts, and screw them by hand for positioning without final tightening.

Tightening and Wiring

1. Tighten the fixing bolts to the original factory torque (usually 8–12N·m) to prevent housing deformation.

2. Wiring sequence:

• First, connect the power cable to the 30 terminal (torque: 18–22N·m).

• Then, connect the field winding wire to the C terminal.

• Finally, plug in the control connector of the 50 terminal.

  Ensure all connections are firm without looseness.

Function Testing

1. Temporarily reconnect the negative terminal of the storage battery, turn the ignition switch to the start position, and check the following items:

• The solenoid switch engages with a crisp sound.

• The pinion pops out normally.

• The engine starts smoothly.

• No jamming, abnormal noise or smoke occurs.

2. Use a multimeter to verify that the 30–C terminals are conducting properly.

Reassembly and Documentation

1. Cut off the power supply again, reinstall the starter protective cover, tighten the starter fixing bolts to the original factory torque (49–64N·m), and permanently reconnect the negative terminal of the storage battery.

2. Record the installation date, torque values applied, keep the Bosch part number and the corresponding page number of the Santana maintenance manual for future reference.

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Precautions for Installation of 12V Bosch Starter Solenoid Switch for Santana

1. Power-off Operation Must Be Performed FirstDisconnect the negative cable of the storage battery before installation to prevent short circuit, ablation or electric shock caused by accidental contact with terminals during the installation process; reconnect the negative terminal after installation, and ensure that the connector is fastened without looseness.
2. Component Matching VerificationConfirm that the new solenoid switch is a Bosch 12V compatible model with terminal markings 30 (power input), C (motor output) and 50 (control signal), which must be fully matched with the original vehicle starter. Mismatched models may lead to weak pull-in or functional failure.
   Inspect the iron core, shift fork hook and return spring of the new switch for deformation or rust, and check that the dust-proof sealing ring is intact without damage.
3. Accurate Mechanical PositioningDuring installation, firmly engage the iron core hook of the solenoid switch into the slot of the starter shift fork to ensure that the shift fork moves smoothly without jamming; positioning deviation will cause the drive gear to fail to pop out or return normally, leading to gear teeth impact and wear failures.
   Align the fixing bolts with the mounting holes before hand-tightening for pre-fixation. Forcing the housing to align by prying is strictly prohibited to prevent deformation of the switch housing and damage to the internal coil.
4. Strict Compliance with Tightening Torque StandardsThe tightening torque for the solenoid switch fixing bolts (M6-M8 specification) is 8–12N·m. Excessive torque will crack the housing, while insufficient torque will cause bolt loosening due to vibration.
   The tightening torque for the power cable nut of the 30 terminal is 18–22N·m. After wiring, pull the cable to confirm no looseness, so as to avoid heating and ablation of the terminal under large current.
5. Non-reversible Wiring SequenceFollow the wiring sequence of 30 terminal → C terminal → 50 terminal: first connect the 30 main power cable, then connect the C terminal to the motor field winding wire, and finally plug in the control connector of the 50 terminal. Reversed wiring is likely to cause circuit short circuit, damaging the switch coil or vehicle electrical appliances.
6. Step-by-step Functional Test VerificationBefore testing, disconnect the starter from the engine flywheel (or ensure the vehicle is in neutral/parking gear) to prevent injury caused by accidental start-up.
   Temporarily connect the negative terminal of the storage battery, turn the ignition switch to the start position, and observe the following: the solenoid switch pulls in with a crisp sound, and the drive gear pops out normally; when the ignition switch is released, the gear must return quickly without jamming or abnormal noise.
   Use a multimeter to detect that the 30 and C terminals conduct well in the pull-in state with resistance approaching 0; after disconnecting the control signal, the 30 and C terminals must be completely disconnected.
7. 
   

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References：

I. Original Factory Technical Documents (Shanghai Volkswagen)

1. Shanghai Volkswagen Santana Maintenance Manual (2012 Edition, applicable to Santana Classic/2000/3000/Vista)

• Power-off Operation Requirement: Disconnect the negative terminal of the storage battery before disassembly to prevent short circuit.

• Torque Specifications: Tightening torque for solenoid switch fixing bolts is 8–12N·m; torque for the power cable nut of Terminal 30 is 18–22N·m.

• Wiring Sequence: 30→C→50; reversed wiring is prohibited.

• Testing Standards: Crisp pull-in sound, normal gear extension/retraction, no jamming or abnormal noise.

• Source Chapter: Electrical System - Starting System (Chapter 9), Sub-section on Starter Disassembly, Assembly and Solenoid Switch Replacement

• Core Basis:
2. Shanghai Volkswagen Technical Bulletin (No.: 44-2015)

• Supplementary Requirements: Perform no-load test on the starter before connecting it to the engine to prevent accidental start-up risks; single start-up duration ≤ 5 seconds, and interval between two start-ups ≥ 15 seconds.

II. Bosch Component Specifications (for 12V Starters Only)

1. Bosch Starter Maintenance Guide (12V Series, Part Nos.: 0001109026 and other compatible models)

• Component Matching: Terminal markings shall be 30/C/50; the iron core hook shall be accurately aligned with the shift fork; dust-proof ring sealing requirements shall be met.

• Tightening Prohibitions: Forcible prying of the housing is strictly prohibited to avoid damage to the internal coil.

• Continuity Test: Resistance between Terminals 30 and C shall be close to 0 when the switch is pulled in; complete disconnection shall be achieved after the control signal is cut off.

• Source: Bosch Automotive Aftermarket Technical Manual (2020 Edition), Chapter on Solenoid Switch Installation

• Core Basis:
2. Bosch Solenoid Switch Technical Parameter Table (12V)

• Standards: Rated coil voltage is 12V; pull-in current ≤ 6A; release current ≤ 1.5A; compliant with ISO 8856 standard.

III. National/Industry Standards

1. QC/T 731-2005 Technical Specifications for Automobile Starter Solenoid Switches

• Installation Tolerance: Position deviation of mounting holes ≤ 0.3mm to prevent housing deformation.

• Protection Rating: IP44; the dust-proof ring shall fit closely to the housing to avoid water ingress and short circuit.

• Durability: No failure after ≥ 5,000 pull-in/release cycles.

• Core Clauses:
2. GB/T 5338-2008 Basic Technical Specifications for Automobile Electrical Equipment

• Safety Requirements: Insulation resistance of wiring terminals ≥ 10MΩ to prevent electric leakage; high-current terminals shall adopt anti-ablation design.

IV. Source Traceability Comparison Table (Precautions vs. Basis)