Clarification on 90 and 115 amp alternators

Hi everyone, can someone please clarify something for me. It is my understanding that the 1990-1992 xj40’s had 90 AMP alternators with a 4 groove pulley and the 1993- 1994 xj40’s had 115 AMP alternators with 5 groove pulley, is this correct ?

The reason i ask is I have a 1990 xj40 4.0 litre Sovereign. The alternator I have removed off the vehicle is a Bosch 115 amp alternator which has the part number DAC 5094.

I am trying to figure out if this vehicle originally came out with the 90 amp alternator or someone has upgraded it or 115 amp unit.

This xj40 has 4 groove pulleys on both the alternator and water pump as well as the harmonic balancer.

There does not appear to be a large alternator suppressor (part number # DBC12319) fitted to the vehicle, only a load dump module. I was under the impression all 115 amp alternators were supposed to have the large red bull can size suppressor fitted.

I am located in Australia so the vehicle is a RHD vehicle. I can give you the vin and engine number if thats of assistance to you.

The reason I am confused is a Jaguar spare parts specialist told me that it must be a 90 amp alternator because it’s a 1990 model. I specifically told him it was a 1990 Sovereign model and he still said it definitely came out with a 90 amp alternator.

Thanks for your time and any assistance you may provide



From the Jaguar “1990 Model Year Update” notice to Dealers, when they introduced the 4.0 litre engine,

"The 1990 MY alternator has an increased output of 115 amps"


Hi Bryan, thanks for the prompt reply and assistance, I appreciate it. When searching in the forum archives I noticed one of your replies to a post, it read as follows;

In reply to a message from Nigel Snowden sent Wed 21 Nov 2012:

‘’A new 120 amp generator provides the necessary current to
satisfy the electrical loads of the vehicle. dive from the
crankshaft pulley is via a five-rib belt that also drives
the coolant pump.

The mounting to the engine and adjustment
arrangement is the same as the previous generator; however
the mounting is by a two-lug bracket.

The new generator has increased low-speed output
characteristics to provide an improved battery load balance.
The improvement is made possible by a different type
regulator and smaller diameter pulley.

Because the new generator incorporates internal overload protection and can
provide the instrument pack with the correct signal for
charge warning, a load dump module is no longer required. A
radio frequency suppression module connected to the
generator is mounted on the left crush tube.’’

I gather that the above information is only referring to the 1993 xj40 and not the 1990 model, I’m confused as my car has the load dump model but doesn’t have suppression module




Presumably the RF surpression module was a new feature for '93 MY, not required (or thought of!) on the earlier models since I can find no reference to it in earlier specs (although I may have missed it)

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Thanks, I think you might be right