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Anti Lock ECU replacement

nlcrane
Spain Rep
Posts: 7604
Joined: Sun Feb 07, 2010 7:36 pm
Location: Spain

Re: Anti Lock ECU replacement

Postby nlcrane » Sat May 18, 2019 10:37 am

I fully agree with Derek, the JHM 1130 manual is the XJ40 bible, I always have a copy handy on my bedside table.
The ABS Main relay is the one with a white housing and a yellow base, (part number DAC 7151) It is a normal relay, five connections, coil plus, coil negative, common terminal, normally open terminal and normally closed terminal, but here is the thing, Jaguar seem to have used a relay with a non standard “pin out” and stuck their logo on it, so plug in another relay and it may not work. There is also a quench diode externally mounted across the relay coil so the polarity must be strictly adhered to.
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1994 Sovereign Gold 4.0

Area rep. SPAIN
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nlcrane
Spain Rep
Posts: 7604
Joined: Sun Feb 07, 2010 7:36 pm
Location: Spain

Re: Anti Lock ECU replacement

Postby nlcrane » Sat May 18, 2019 1:05 pm

Even though I am retired, it must be the engineer in me, I just couldn’t leave it alone so I searched my spare stash and stripped down and compared a White housing relay (DAC 7151) and a Green housing relay, these being the only two on the forty with a 5 pin out, namely 85 and 86 (coil), 30 (Common), 87a (normally open) and 87 (Normally closed) and they are both the same. I also compared them to a new (bought on ebay, generic 5 pin relay) and it also was the same. I can only surmise that the later MY models with ABS used a “later” or newer Siemens relay instead of the earlier Hella types. Hope this helps out.

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1994 Sovereign Gold 4.0

Area rep. SPAIN
espana.xj40@googlemail.com

nlcrane
Spain Rep
Posts: 7604
Joined: Sun Feb 07, 2010 7:36 pm
Location: Spain

Re: Anti Lock ECU replacement

Postby nlcrane » Sat May 18, 2019 2:54 pm

A relay is a relay and having said that I have to add that the quality of a Siemens or Hella relay as opposed to an Oriental lookalike bought on ebay will obviously be different.
Just like a Louis Vuitton bag bought on 5th Avenue, New York is not the same as the “Louis Button” bag sold by a very colourful figure from his display blanket spread on the promenade in Salou, Spain.
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1994 Sovereign Gold 4.0

Area rep. SPAIN
espana.xj40@googlemail.com

Bruce69
Posts: 76
Joined: Wed Apr 04, 2018 2:16 pm

Re: Anti Lock ECU replacement

Postby Bruce69 » Tue Jun 04, 2019 2:45 pm

Inserted new relay and everything is working. Hurrah!

Disassembly of the old relay revealed no obvious fault but even testing across the winding terminals got several megaohms (would post a picture of the pristine insides of the relay but I can't see the buttons to upload :? )
XJ40 3.2 LPG 1991 54k
Jeep Grand Cherokee Overland 4.7 V8 HP LPG 2002
Dodge Charger R/T 1969