77 front cooling fan skematics WSM 78 not correct
05-26-2015, 06:32 PM
#1
Race Car
Thread Starter
77 front cooling fan skematics WSM 78 not correct
Looking for an 77 schematic on the cooling fan circuit and pin out of the XVIII relay.
My front cooling fan is intermittent from what I see on the 78 WSM XVIII should be a 53 style relay grounded by the air conditioning thermal switch or raditor temp switch. Since this is connected to the X bus it should be active only with key on. If I connect either switch with a jumper wire the fan turns on with key off. The relay installed is an 928.615.111.00 so the 79 skematics must not be correct. That said from what I have researched this setup is minamum at best apparently even if the compressor is on the fan only runs when compressor tempature gets hot. The fan intermittently runs after car is off for about 3-minutes which may be normal with the relay XVIII.
Any help would be appreciated.
It is possible that the radiator temp sensor is bad but need a good skematic to diagnose this issue.
My front cooling fan is intermittent from what I see on the 78 WSM XVIII should be a 53 style relay grounded by the air conditioning thermal switch or raditor temp switch. Since this is connected to the X bus it should be active only with key on. If I connect either switch with a jumper wire the fan turns on with key off. The relay installed is an 928.615.111.00 so the 79 skematics must not be correct. That said from what I have researched this setup is minamum at best apparently even if the compressor is on the fan only runs when compressor tempature gets hot. The fan intermittently runs after car is off for about 3-minutes which may be normal with the relay XVIII.
Any help would be appreciated.
It is possible that the radiator temp sensor is bad but need a good skematic to diagnose this issue.
05-26-2015, 06:38 PM
#2
Race Car
Thread Starter
It's a 100 degrees in the garage I jut pulled the XVIII relay and it's a huge style 53 so the skematic is correct but I cannot find a replacment relay any one know of a cross reference and currant rating?
05-26-2015, 07:31 PM
#3
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928 615 111 00 is NLA but I am sure Mark at 928Int. has plenty of used ones.
Used from 77 to 82 and then changed to a 53B - try a 53B.
Used from 77 to 82 and then changed to a 53B - try a 53B.
__________________
Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission?
George Layton March 2014
928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission?
George Layton March 2014928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
05-26-2015, 10:21 PM
#4
Race Car
Thread Starter
I need to know if this relay is powered by the X bus, if not power is finding its way there. On A3 the Xbus turns on with the key so either a short from the 30 bus or the way it's powered for that year is different. If the fan runs with the key off then it's not connected to the Xbus maybe someone has this year that can answer this ?.