First of all, there are serious errors in that ECU/FP relay part of the
88/89 Bentley Digifant diagrams, with connections shown wrong. Second,
the change to the more complex ECU relay with diode did not occur
exactly on the 88 model year break so your 88 may have come with the 87
type FI harness.

That diode is NOT being used as a suppressing diode.

Mark

neil n wrote:
> Hi all.
>
> Am finding a bit of poor work and mysterious things in my 1988 Westy
> engine bay.
>
> Situation: engine bay wiring harness likely replaced. ECU and fuel
> pump relays are both 4 pin Hella 53. Relay diagram shows what may be a
> suppressing diode in parallel at relay coil.
>
> The van runs, but because a 4 pin instead of 5 pin relay is used for
> ECU, and that there are 2 less wires going to this relay, am concerned
> that the ECU may run the risk of voltage surging through it when
> engine shut down.
>
> This isn't rocket surgery but my mind is drawing a blank. It appears
> that the new harness is wired to incorporate the (I assume) diode on
> the ECU relay, but if someone can confirm that is the case, I'd
> greatly appreciated it.
>
> Here's an image showing wires to the ECU and FP relays:
>
> https://lh4.googleusercontent.com/-WSBT0EaD1TY/T8QS2Nc_5bI/AAAAAAAAFzM/3jfPMADDoG4/s640/Digifant%2520ECU%2520Relay.jpg
>
> ECU relay:
>
> 86: Black. Confirmed  +  from 15.
>
> 85: Two brown wires. Confirmed ground to frame.
>
> 30: two red wires. Confirmed from B+ One goes to FP relay 30
>
> 87: Red/White,  White wires. Confirmed to PS sensor. I assume one wire
> goes to ECU as vehicle runs! Don't know about idle stabilization
> module.
>
>
> FP relay
>
> 86 Black-White wire: + from 15  ?
>
> 85: White w/Red printing (not shown). Ground from ECU ?
>
> 30: Red. B+ confirmed
>
> Since the FP works, (cycles on/off key turned to 15, vehicle runs) I
> haven't tested these wires.
>
> Thanks for any insights,
>
> Neil.
>
>