w124 e320 wont start immobilser, ecu or wiring loom

[kth286]

Nope it is footwell mounted as I describe. Unfortunately, there are significant differences between 93 - 96 W124 UK spec cars in terms of the alarm/immobiliser and other cars intended for other markets such as North America. In the early 90s the UK was suffering from lots of car thefts and insurance companies insisted on specific approved alarms which lead to MB partnering in the UK with Scorpion and branding it as MBSS. The unit I have in my Cabriolet is the more sophisticated version but I also had a 94 W124 E320 estate that had the less sophisticated MB Scorpion unit which worked by rf remotes as Dec shows early in this thread. Interestingly enough that unit failed too and I have a brand new unit that a bought as a spare still in the box

Yes - the later 124 (starting model year 1996) the remote central locking
is enhanced with so called drive authorisation system (DAS), stage 2.

Previously a starter lock-out system is installed which interrupts circuit 50 to the starter.

Boomtings:

I am not suggesting main earth W1 behind cluster is loose enough to shake about going over bumps. If it is corroded, it will be causing a high voltage resistance depending on weather conditions, causing the voltage to be too low to operate circuit relays & components on occasions - just like the fuses in the fuse boxes of 124s corrode and break circuits intermittently.

 

[boomtings]

Thanks I really appreciate the information and assistance.

I can confirm I have new batteries and resynced.

thanks for explaining the ground.

I tried to locate the relay but did not see it behind the cluster. I was trying to bypass the alarm/immo as I thought it would help fault find. Ill take it apart again on the weekend and take photos.

 

[RBYCC]

Thanks I really appreciate the information and assistance.

I can confirm I have new batteries and resynced.

thanks for explaining the ground.

I tried to locate the relay but did not see it behind the cluster. I was trying to bypass the alarm/immo as I thought it would help fault find. Ill take it apart again on the weekend and take photos.

Did you go to page 00-B.2/6 Figure 24?
If you have one that's where it will be...

http://johnmeister.com/DieselBenz/TECH/Overvoltage-Relay/relay_control.pdf

 

[boomtings]

Did you go to page 00-B.2/6 Figure 24?
If you have one that's where it will be...

http://johnmeister.com/DieselBenz/TECH/Overvoltage-Relay/relay_control.pdf

Ed ,I am sure that I looked in the same location last weekend just before it started again. This weekend I will try to go back and have another look.


I reread the owners manual last night and then Billys project thread. I was suprised to read in the manual
how on manual seats headrests heights are adjustable by using the dial on the side of the seat base. I wonder how many people just used their hand?

About to enter underground on the tube.

 

[RBYCC]

Not sure if this has been posted and it is for the non remote actuated ATA North American delivery cars.
It shows the K38 relay location and how to bridge it ...of course if you have one

How-to: Disable alarm on a 1993+ W124 - PeachParts Mercedes ShopForum

 

[boomtings]

Boomtings:

I am not suggesting main earth W1 behind cluster is loose enough to shake about going over bumps. If it is corroded, it will be causing a high voltage resistance depending on weather conditions, causing the voltage to be too low to operate circuit relays & components on occasions - just like the fuses in the fuse boxes of 124s corrode and break circuits intermittently.

I had the instrument cluster out today looking for the k38 relay for the immobiliser and can confirm its not located behind the cluster.

Kth286 was spot on as I used my phone to photograph the Earth W1. I saw a little corrosion so unbolted and gave it all a clean as best I can with the access available. I tested it unbolted and got a similar no start. I rebolted evefythinv back up and await as this isan intermittent problem.

I also had a peek behind the footplate and its the cruise control unit that is clicking when ignition is primed.

Im hoping that the earth clean up has cured it but only time will tell. So the mystery is where did mercedes relocate this relay.

I have taken photos and will put them up when I can.

 

[219]

As above, its unlikely to be immobiliser. Check for spark at each plug. Check distributor and rotor arm.

The 320 has distributor less ignition .

 

[RBYCC]

If the UK cars had some hybrid system as a few posts have suggested, then possible you don't have a K38 relay and the immobiliser is built into the control.

Can you post a pic of your control unit?

Ed A.

 

[boomtings]

If the UK cars had some hybrid system as a few posts have suggested, then possible you don't have a K38 relay and the immobiliser is built into the control.

Can you post a pic of your control unit?

Ed A.

Hi Ed.

Will post the pics of everything discussed as soon as I get a chance to put them up. They will hopefully help someone else.

Could it be a left hand drive thing? So on rhs its behind airbag?

For now I can report no starting issues.

 

[RBYCC]

Hi Ed.

Will post the pics of everything discussed as soon as I get a chance to put them up. They will hopefully help someone else.

Could it be a left hand drive thing? So on rhs its behind airbag?

For now I can report no starting issues.

I hope not....

So the clean up of the earth is allowing you to start?
That's great and hopefully an easy quick fix to the problem !!!
Fortunately USA cars don't have the same level of corrosion as in the UK.

Let's assume that you do have a UK only hybrid control unit.
Make and any part number will hopefully allow for the ability to figure out the pin out/wiring.

Any circuit can be jumpered/bridged if the wiring can be determined.

Ed A.

 

[219]

I also had a peek behind the footplate and its the cruise control unit that is clicking when ignition is primed.

The cruise control amplifier on every W124 I have seen , and most other models as well , is up above the brake and accelerator pedals in the drivers' footwell . I don't recall any of them ever making clicking noises ( can't recall whether they have relays inside ) . The cruise control system comprises of only four components : control stalk , speed sensor ( either attached to the rear of or integrated into the speedometer ) , amplifier and throttle actuator ( in the engine compartment ) .

 

[boomtings]

Heres the pics of the area where the K38 should be.

The Earth points are behind the righthand side of the instrument cluster , they are just visible, however using a camera I was able to get a better view.

I am at the moment very confident that this was the issue! :bannana: :bannana:

here are the parts behind the footplate. (My 5 yr old son took it)

part numbers 124 545 51 32 and single plug alarm unit 140 820 67 26

hope they help someone.

 

[grober]

The bigger unit A1245455132 is I believe part of the cruise control unit.

 

[bolide]

That's the cruise ECU on the left. 280s and 320s with HFM had a cruise ECU instead of the cruise amp used in earlier cars & diesels.

The cruise ECU connects to the TB via a dedicated cable and the TB spur off the main loom is not used. There are other cables coming into the cruise ECU as well - they will be from the engine ECU & etc

I had a car recently that wouldn't idle. It required a TB and a cruise ECU so I got to know the system quite well...

Nick Froome

 

[RBYCC]

Good news is that the module on the right is a standard Merc Temic alarm system used in USA W140 and R129's . This style did not use the K38 relay that was used with the Becker unit.

BURGLARY ALARM SYSTEM AND INFRARED CLOSING SYSTEM. Fits: Mercedes | Mercedes-Benz of South Atlanta

 

[grober]

Temic Theft Alarm Mercedes R129 R170 W140 W163 W202 W208 W210 W215 W220 Chassis | eBay-----------????

 

[RBYCC]

For future reference...

Not sure what applies to your late model 124.

It appears the Temic unit used in the W140 still uses a K38 relay mounted under the hood in the relal box aft of the fuse box.

http://www.mbcluster.com/Media_Pictures/W140 Combination Relay.pdf

http://mercedes-bulgaria.com/Downlo... Equipment/Anti-Theft Alarm-ATA/Model 129.pdf

http://mercedes-bulgaria.com/Downlo... Equipment/Anti-Theft Alarm-ATA/Model 202.pdf

Mercedes Wiring

Sooner or later as they age, the majority of Mercs will have problems with the alarm system.

Ed A.

 

[boomtings]

Thanks for those last links, never seen the wiring site before.

I can confirm that ive not had a single intermittent start problem. My idle has also come back to the correct level after clearing pin8 .

 

[bolide]

When the ATA Anti Theft unit failed on my 1995 E300 Diesel I looked for, and failed to find, a relay behind the binnacle

I am finding the convenience/comfort module to be a prime source of electrical gremlins

Nick Froome

 

[Alex camilleri]

no fuel or spark

Hi guys,
i have a mercedes w124 1994 220 ce.
A couple of months ago the wiring from my air flow sensor melted itself and the car cut out.
After this happened my car would not start atall. Theres no fuel pump kicking in and no spark.
So i decided to buy a second hand wire loom in good condition. After fitting the new loom i still have the issue of no spark or fuel pump kicking in. Iv hard wired the fuel pump and seems to work fine.
Does anyone have any suggestions of what would cause this?
Thanks in advance guys
Alex