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FOR BMW 325d 330d 525d 530d 535d 635d X3 X5 X6 HERTH & BUSS GLOW PLUG RELAY UNIT
FOR BMW 325d 330d 525d 530d 535d 635d X3 X5 X6 HERTH & BUSS GLOW PLUG RELAY UNIT
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Description
Description
BMW 325d E90
BMW 325d E91
BMW 330d E91
BMW 325d E92
BMW 330d E92
BMW 325d E93
BMW 330d E93
BMW 525d E60
BMW 525d E61
BMW 530d E60
BMW 530d E61
BMW 535d E60
BMW 535d E61
BMW 635d E63
BMW 635d E64
BMW 730d & 730Ld E65 E66 E67
BMW X3 3.0d E83
BMW X3 3.0 sd E83
BMW X5 3.0d E53
BMW X5 30d E70
What is a glow plug control module?
As you already know, a glow plug is a heating device in each cylinder of a diesel engine that helps the engine to start. But how is the overall operation of your glow plugs monitored and controlled? This is done by a glow plug control module.
Located on the engine and with a direct connection to the engine control unit, the control module uses a microprocessor to analyse input from the engine control unit to determine information related to the working of the glow plugs. This includes when to switch the current for the glow plugs on and off, and how much current is required as this will differ depending on the starting temperature of the engine. The current to the glow plugs is turned on during the pre-heating to warm up the engine, stand-by time when the engine should be started, and post-heating to meet increasingly strict exhaust gas standards and optimisation of combustion processes.
When you start up a diesel-powered vehicle, the following actions happen:
1.The glow plug control module determines the timing and electric current required by the glow plugs based on input from the Engine Control Unit;
2.The heating element in the glow plug is electrified so it heats up and emits visible light (hence the name);
3.Intake air is compressed;
4.The fuel injector spray directs fuel onto the hot tip of the glow plug;
5.The injected fuel mixes with the compressed air, evaporates and starts combustion almost simultaneously, even when the engine is cold;
6.The glow plug remains on during the pre-heating phase to ensure correct combustion of the fuel and reduce the environmental impact of your car.
This process is helped by the increase in temperature of the intake air during compression and the relatively low ignition temperature of diesel. However, a glow plug control module is still essential, as without it controlling your glow plugs, the compression temperature might not be high enough to ensure proper ignition of the injected fuel in a cold diesel engine. This would result in increased exhaust emissions.
What are the symptoms of a defective glow plug control module?
A diesel engine has one glow plug control module which controls the glow plugs. This means that you might not notice when a single glow plug goes bad as this only affects one cylinder in your engine. However, if two of three go bad or the control module itself malfunctions, you’ll quickly find it difficult to start the engine. In addition to watching out for the glow plug light on your dashboard, here are some common symptoms of a defective glow plug or glow plug control module:
1.White exhaust smoke – a defective glow plug will cause diesel to leak into the exhaust where it burns.
2.Hard to start – this could mean the engine is slow to start in warm weather or fails to start in cold weather. However, this can also be a symptom of a problem in the fuel system or battery.
3.Poor engine power – after a difficult start, bad glow plugs will make it difficult for your car to run properly, due to improper combustion which reduces power and efficiency.
How can you test your glow plug control module?
First things first, is it a problem with your glow plugs or your glow plug control module?
The easiest is to check your glow plugs before testing your glow plug control module.
To test your glow plugs, simply connect a 12-volt test light to the positive battery terminal. Then disconnect the wires from each of your glow plugs and touch the probe of the test light to the terminal of the glow plug itself (not the wiring harness). If the light doesn’t light up, the glow plug is bad and should be replaced.
Easier is to use a professional glow plug tester device.
There is some discussion about whether you should only replace the glow plugs that have gone bad, or if it is best to replace them all. As one glow plug going bad could be a sign that the others will shortly follow, some experts recommend replacing them all at the same time while others suggest keeping a close eye on the remaining glow plugs.
If your glow plugs are all working correctly, move onto your glow plug control module. Start by checking the battery voltage to the glow plug control module, a voltage drop of over a half volt (or more) means your control module should be replaced.
Please send us your VIN/Chassis/Registration number for your vehicle after purchasing via an eBay message. This information is required so we can process the correct part for your vehicle. Without the VIN/Chassis number, your order will be put on hold and will delay the delivery time.
Shipping
Shipping
Shipping Times
We will endeavour to deliver your order within 3–5 working days, provided the goods are in stock, unless a longer delivery period is clearly stated on the specific product page.
If we are unable to meet this delivery timeframe, we will contact you within 5 days of receiving your order to arrange an alternative delivery date. If the alternative date is not suitable, you will have the option to cancel your order and receive a refund.
Please note that deliveries to Northern Ireland, the Isle of Man, the Isles of Scilly, the Scottish Highlands, and Scottish Islands may take longer than 3–5 working days. Please contact us before ordering if express delivery is required.
In some cases, we may contact you with a shipping quote where the cost of delivery to your chosen destination is not available at the time of order.
UK Delivery
We offer free delivery across mainland UK, unless otherwise stated.
Additional delivery surcharges apply to the following postcodes and areas:
AB31–AB56, BT, GY, HS, IM, IV, JE, KW, PA20–PA78, PH, PO, ZE, and all offshore islands.
For UK customers, all applicable postage, taxes, and charges shown at checkout must be paid upfront. Tracking is included where available, allowing you to monitor your order through to delivery.
International Customers
Standard international delivery is usually provided on a Delivered Duties Unpaid (DDU) basis.
This means duties and taxes are not paid at checkout. The buyer will be responsible for paying any duties, taxes, customs fees, or carrier charges required upon delivery in the destination country.
Where international shipping costs are not available at checkout, we may contact you with a delivery quote before dispatching your order.
Why Choose A to Z Motor Spares Wakefield?
A to Z Motor Spares
Family-Owned & Trusted Since the 80s
With over 20 years of trading experience, we are a family-run business passionate about providing top-quality car parts at unbeatable prices. Our long history in the industry means you can trust us to provide the right parts for your car.
A to Z Motor Spares
Direct from Manufacturer
We buy directly from UK-based manufacturers, cutting out the middleman. This direct supply chain allows us to offer car parts at up to 30% cheaper than high street stores. Plus, our focus on UK suppliers ensures we help keep jobs local.
A to Z Motor Spares
High-Quality, UK-Based Products
We only work with trusted UK suppliers and manufacturers, ensuring you receive high-quality, reliable car parts. Whether you're looking for regular maintenance items or specific MOT parts, we have you covered.
Trusted by leading brands
