Restricted Performance: P1474 /

not very much on the forum regarding the P1474, so any and all advice and comments very welcome.

i recently washed the car, with some water getting under the hood. Don't know if this is related . But as one older post by Graham ( @GGG )
suggests, driving thru standing water is connected to the P1474, I thought I’d better mention it:

https://www.jaguarforums.com/forum/xk8-xkr-x100-17/p1474-restricted-performance-87196/#post645871


I don’t seem to be getting any power to the intercooler pump with the ignition key on. The fuse is OK and there is power at the fuse (#2 / 20 amp). The 2 wire connector going into the pump shows no sign of voltage with key on.

Related ? : the throttle body is making a new sound with the key on: a higher pitch whine than I think is normal, like it’s trying to make a connection, but can’t ? Rapidly intermittent. I hope the throttle body sideshow is not a rabbit hole, but wanted to list any anomalies than seem relevant.

Thanks,

Z

 

2001/2 XKR? if so, comments as below based on electrical guide/DTCs for 2001/2

if no power at pump and fuse OK, then as I expect you saw from the schematics, ECU does not monitor actual pump operation (relay contacts), only the relay coil (EM31), so if it throws the DTC then focus presumably should be on the relay coil, not the contacts.
- dodgy contacts on relay box (EM31)
- bad relay (EM31) - open circuit on coil?
- no ground at coil pin 2 (B wire, EM831)
- no +12V power at coil pin 1 from ECU EM80-14 with ignition on (interestingly the electrical guide lists EM80-14 active as Gnd and inactive as +12V, which seems backwards since the other end of the coil shows ground, not +12V)
- open circuit wiring (RW wire from EM80-14 to coil pin 1)
- bad ECU driver transistor (U804, NEC D16801B - can't find a data sheet...5 pin TO220 package), pin 4 goes to EM80-14
- other???

 

Thank you for the response.

I think I have it solved, but I like to put 100+ miles on any fix before I give it an “OK / SOLVED” merit badge.

NOTE: don’t do like I did, and immediately go for a bad intercooler pump just because you can’t hear / feel it running, and tear out the air box. Subsequently go thru all the testing that the manual lists. By which time it’s midnight and dinner has been cold for hours.


No, don’t do all that first. Instead , do like a monkey does: First just dig out a spare 4 blade relay and just try that . That will only take 5 minutes and cost nothing because everyone has a spare relay, at least one.

Damn relays. Can’t they make a relay that lasts more than 22 years ?


Z