348 Starter Relay Modification

Looking at the diagram "Fig 11a" (5.2 355), the negative side of the relay "P" coil is connected to the starter solenoid on which it relies for proper connection to the ground (when the key is in RUN position). Inserting a cube type starter relay may not have any effect on the Bosch ABS circuitry (no orange relay) but will cause the relay "P" to operate at only 6V at which the relay may not switch "on". Or is the relay "P" wired differently in the case of Bosch ABS?

Is the diagram on "Fig 11a" also applicable to the 5.2 355 with Bosch ABS?

I see on the diagram "Fig 12b" (F1 cars) that there is a cube relay to disable START under certain circumstances. This relay, although called "starter relay" on the diagram, is not wired like a proper starter relay but is wired with its contacts "in-line", i.e. inserted in the wire going from the key switch to the starter solenoid. If this is correct, then the relay just prevents the power from the key switch from reaching the starter solenoid and does not alter the link from the relay "P" to the starter solenoid. Inserting an additional cube starter relay will still cause he relay "P" (if wired like on the diagram "Fig 11a") to run at 6V.

I may be incorrect to some extent because I have not really studied the 355 diagrams much so I stand to be corrected.

 

On F355 5.2 cars (6 speed, not F1) at least some cars are fitted with a relay for the purposes of reducing current through the ignition switch and for the purposes of stopping cranking as it is connected to the Immobiliser ECU. This is the way my early 1998 car is wired up. On my car, there is no reduced voltage reaching relay P because the coil of the starter (inhibit) relay is not connected to the coil of relay P. The coil is only connected to the Immobiliser system.

Here is my latest 11a diagram:
https://www.dropbox.com/t/zSRw5isrbtIBMMS5

I can't be sure that all 6 speed 5.2 cars are wired up like this, so you may be right about reduced power at relay P on some cars. My car is wired up in the same fashion as the 1997 paper charts I have. I can't say if late 1998 or 99 cars are wired up differently. If your 11a diagram is different, it may have been my early interpretation of how the system worked (before I got my hands on some genuine paper 5.2 diagrams)

What's confusing about the Bosch wiring is that there is a white wire going to the main (car/brake system) interface plug from the start system, but the wire ends there and doesn't go to the Brake System ECU or pump relay. Maybe the pump uses less power, so doesn't need to be cut out during start.

Bosch diagram:

https://www.dropbox.com/t/iB6HdLOcrnR5BWji

On the F1 version, the starter relay has to be enabled by the F1 system and this is done via the coil. The immobiliser system has no input into the starter system on the F1 car. These cars seem to have reverted back to where the full starter current goes through the ignition lock. The F1 car has to have a starter enable relay because you don't want the car to be started with the car in gear. It has no clutch pedal. I use the word "enable" rather than "disable", because without the F1 system being operative, the starter relay won't default to start. Again, there is no reduction of power at relay P, because the coil is not connected to the starter coil.

 

Does anyone know whether the Bosch WR-1 kit is still available as I can’t find one online? If they do still exist, is the fitting universal for any car or are the lead fittings specific to the 348?
Thanks

Jon

 

I have recently seen it offered on Ebay and by about 20 online sellers. How did you search for it?

 

Same here. I found no difficulty finding it. Perhaps your Google search has country filters.

I assume the kit intercepts the normal start signal from the key, but uses a live battery source in the engine bay for solenoid activation (via pins 30 & 87 of the relay).

Would the circular lug in the kits on eBay be large enough to go on the main starter contact?

Jon, do you have any wirestripping and lug crimping tools if the kit is not 100% compatible?

 

I’m based in the UK and there are a couple of WR-1’s in the search results but these are for VW cars and campers and the colour cording of wires is different. Have tried rock autos in the USA but this shows as item out of stock.

 

They all operate in a similar manner. Only the wire length may be different. That's why I asked about wirestripping and crimping. We can create a wiring diagram for you if you get stuck.

 

Looking at the VW/Porsche kits...

The red wire with the inline fuse goes to a live battery source (such as the terminal strip in the engine bay on the (EDIT) right hand side under the cover marked "+"). Looking at online photos of the 348 engine bay, the cover on the terminal strip may have broken off and disappeared.

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To be confirmed... Perhaps you could post a closeup photo of the kit's relay socket:
The female spade connector (white) would most likely attach to your starter solenoid.
The male spade connector would attach to the old wiring coming from start switch (which originally went to the starter solenoid connector).
There should be some black earth wires to attach to the chassis.

Miro? @m.stojanovic

With this mod, a lot less current needs to flow through your ignition switch (and wiring), so less wear and tear on the switch. The fused red wire adds protection to the power circuits. Previously there was none on the starter circuit.
Just make sure the new relay is away from water and heat.

 

The WR-1 kit is universal and many of them I have seen, irrespective of what car they are advertised for, seem to have the wire colours, lengths and terminals similar to what is shown on one of the attached pictures in post #53 above with which it should be easy to compare any WR-1 you find online before you buy it. Also, one of the pictures above shows the wiring diagram (which practically applies to any car). The only a bit strange thing is that WR-1 has a Yellow wire going to the ground and a black wire going to the starter solenoid but one should follow the diagram anyway. Here's one from Ebay:

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I got mine off of amazon with a sealed relay.

https://www.amazon.com/gp/product/B01CXA42XK/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

remember, you're only controlling the solenoid, not the actual starter.

 

Looks great Steve, especially so as it’s waterproof. Did you fit it to your 348 successfully?

 

Yep...5 years ago. I take my car out weekly.

 

You could just buy the components seperately and make your own kit.

You can buy the relay off Amazon or only £3.68 here:

https://www.almsolutions.co.uk/index.php?main_page=product_info&products_id=1955

I bet if you gave them a call and sent them an email with a pic of what your trying to do they could supply all the bits

 

Steve I’ve ordered one of these - would you be able to give me guidance on which terminal and wire goes where?

 

sure. I thought it was somewhere in the thread....but maybe not.

the existing wire to the solenoid is now the signal wire in the relay. (goes to one wire of relay, other signal wire goes to ground)
The power wire on the relay steals the + from the starter wire (which comes directly from the battery), and goes to the solenoid. so...B+ -> relay -> solenoid.

Be sure to clean the big bullet connector under the air box (early 348)

 

Thanks Steve but I’m a bit confused (not having done this before!)

Below is a photo of the wiring diagram that came with the Fastronix relay which arrived today, but I can’t relate it to the wiring on my 348.

Could you possibly indicate/ annotate what 348 wire goes to which fastronix wire?

Also - the wires in the relay are very short and don’t include an inline fuse - did you lengthen yours and add a fuse yourself? Also where did you mount it please?

sorry for the dumb questions - I just don’t want to set my car on fire!

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Thanks Ian!

Beat me to it.

@MLX_1 Clear?

 

Bingo!

Ian/Steve Thankyou very much!

 

Good morning all, hope things are well!

I am calling in for help/back up to get me over the final hurdle of this Sunday morning project. Unfortunately, some of the data/instructions here don't exactly align with my '89 model.

Here is a short video of where I am.


This should provide a good visual for anyone else tackling this project in the future of where you will roughly land. I will capture and upload another video for crystal clear instructions once I am guided into the correct wiring orientation to get this buttoned up and to work. Thanks to any and all who can help here, look forward to hearing from y'all!


Also, summarizing the original instructions here:

Terminal 30 - Battery positive voltage supply

Terminal 86 - Ground

Terminal 85 - Power from the ignition switch starting position

Terminal 87 - Power out to starter solenoid

First, identify the wire from the ignition switch. White wire, 4th from the left, in terminal block D (black). Snip this wire and run it to terminal 85 on the new relay, bypassing the fuse panel.

Snip the white wire directly behind the first wire, in terminal block A (yellow), 4th from the left, and connect it to terminal 87 on the relay.

 

Update, I got down there with a test light and confirmed that I had the correct wire grabbing signal from the ignition switch... And that I also had the correct wire running to terminal 87 to feed the starter.

The reason my starter wasn't getting power is because the damn connection at the relay wasn't biting the wire well. With that said, and correct me if I'm wrong, my video should clearly visualize the correct way to wire this relay up, just ensure your connections are FULLY fastened and secure haha!

 

I guess the wiring depends on what you’re trying to achieve…

1) remove the high currents from the ignition switch and/or
2) remove the high currents from the relay panel and/or
3) remove the high currents from most of the car wiring up to the engine bay, including the sometimes dodgy circular connector near the rear left hand rear strut (found on most cars) and/or
4) put the relay in an unseen/ weather-protected place

In your installation, you’ve chosen 1), 2) and 4).

I’m not sure what you mean when you say you have no terminal block D? D is the yellow one in the middle of the board (LHS)

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A standard connection (convention) of relay pins 85 & 86 is 85 to ground, 86 to positive supply. It does not matter if it is the other way round as long as you don't use a relay which has a blocking diode across terminals 85 & 86. If such relay is wired to receive positive supply on pin 85, it will blow the diode.