Discovery 1 94 , no heaters, wipers, mirrors, windows

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r8hilbocus

r8hilbocus

Member
Posts
20
Location
london
Hi all,
I need help with some electrical troubleshooting on a 94 300tdi.
After filling up the coolant system and running it for the first time in a while I went to switch on the heaters but nothing, then tried wipers, windows, electric mirrors - all dead! Lights work and everything runs fine engine wise but for some reason these auxiliaries have all stopped. I'm not sure if welding could have caused any issues with the circuitry as the last time I tried these everything worked but I always disconnect the battery anyway.
I then looked at the relays in the footwell and bridged terminal 30 and 87 on the rear most relay and the blowers started working, this tells me that the motors, switches and fuses are fine but something is wrong with the feed or ground, not sure where the relays for all the other auxiliaries are but there must be a single problem causing it all? Does anyone know why it will only operate by bypassing the relay and if this is affecting everything else?
Thanks
 
Hi, i usually dont answer to those who are not following the "protocol" with this https://www.landyzone.co.uk/forum/introduce-yourself.20/ but now i'm in a good mood so i can give you just a hint: check the connection at earth header E201/C2029 which provides the earth for the relay's coils of the systems you mentioned

1713820221174.png
 
r8hilbocus said:
Thanks mate that's really useful I'll check that earth tomorrow!
I'll introduce myself now!
Click to expand...
Welcome just be aware that my reply is based on the '95 modell diagrams as the for earlyer modells are very hard to find but i presume that 94 with 95 300tdi should be quite similar
 
lynall said:
Google fusible links, 200 had them but not sure on the 300?
Click to expand...
Sorry to correct you but afaik those are present on up to 92 modells only and as long as the blower started when it's relay's contact was bridged means that there is power on the circuits just that the relays are not closing hence my suspicion that there is a problem on the involved relay's coils circuit and the earth i pointed to goes to those mentioned in the first post ;) .
 
sierrafery said:
Sorry to correct you but afaik those are present on up to 92 modells only and as long as the blower started when it's relay's contact was bridged means that there is power on the circuits just that the relays are not closing hence my suspicion that there is a problem on the involved relay's coils circuit and the earth i pointed to goes to those mentioned in the first post ;) .
Click to expand...
That's the clever logic I was looking for, bypassing the relay seemed to narrow it down!👏
 
discool said:
The 1995MY D1 with its 300tdi engine was introduced in March 1994, and of course it has “fusible links” located in the engine bay fusebox.
The 1994MY D1 had the 200tdi engine.

Just saying for those that are uncertain 🤔😊
Click to expand...
Is there a way of telling how early of a 300 it is by the registration? The old british plate was L807 LGM
 
discool said:
The 1995MY D1 with its 300tdi engine was introduced in March 1994, and of course it has “fusible links” located in the engine bay fusebox.
The 1994MY D1 had the 200tdi engine.

Just saying for those that are uncertain 🤔😊
Click to expand...
My reply was to:
lynall said:
Google fusible links, 200 had them but not sure on the 300?
Click to expand...
so i was convinced that mr @lynall was thinking to what's in the attachment

just saying for those who misunderstood my reply :)

even though it's quite irrelevant for the topic's subject.
 

Attachments

  • Discovery 1 up to 94_fusible_link_repair (1).pdf
    286.6 KB · Views: 135
r8hilbocus said:
Is there a way of telling how early of a 300 it is by the registration? The old british plate was L807 LGM
Click to expand...
The L prefix registered vehicles were from August 1993 to July 1994 your reg certificate will give the first date.

1993 D1s were fitted with the 200 engine, but some owners in the past have mentioned in the forums that their early vehicles had the 300 tdi but the electric wiring was still that of the 200 series… which among other things doesn't have an engine bay fuse box.
 
r8hilbocus said:
Thanks mate that's really useful I'll check that earth tomorrow!
I'll introduce myself now!
Click to expand...
Another thing to do is to remove the blower relay you bridged or the windfow lift relay or wiper relay and see what's missing on the coil's path which means a continuity check to earth in the cavity with the black wire and voltage check with the system switched on against earth in the opposite cavity if you see what i mean... once you know what's missing in those systems relay's coil circuit the troubleshooting becomes less complicated
 
Last edited:
sierrafery said:
Sorry to correct you but afaik those are present on up to 92 modells only and as long as the blower started when it's relay's contact was bridged means that there is power on the circuits just that the relays are not closing hence my suspicion that there is a problem on the involved relay's coils circuit and the earth i pointed to goes to those mentioned in the first post ;) .
Click to expand...
My old L reg 1993 200 had them, I know for certain as next owner had one go causing all sorts of grief, took his auto electrician hrs to suss what was wrong!
 
discool said:
The L prefix registered vehicles were from August 1993 to July 1994 your reg certificate will give the first date.

1993 D1s were fitted with the 200 engine, but some owners in the past have mentioned in the forums that their early vehicles had the 300 tdi but the electric wiring was still that of the 200 series… which among other things doesn't have an engine bay fuse box.
Click to expand...
My August 94 D1 has always had a private plate, from it being delivered to the first owners estate, so I can only assume it will be on an M reg plate.
 
sierrafery said:
Another thing to do is to remove the blower relay you bridged or the windfow lift relay or wiper relay and see what's missing on the coil's path which means a continuity check to earth in the cavity with the black wire and voltage check with the system switched on against earth in the opposite cavity if you see what i mean... once you know what's missing in those systems relay's coil circuit the troubleshooting becomes less complicated
Click to expand...
I just checked the resistance between the footwell earth plug and the body, it was zero showing the earth point is good, I then measured the resistance between one of the black wires on the relays and the earth plug and it showed over 100 which is confusing? Also if I have the engine fusebox with the larger square fusible links does it mean there isn't any of the spliced fuses in the diagram you posted?

Thanks
1713894263890.png
 
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I'm also wondering if there's a short somewhere as the feed to the coil side of the heater relay is showing continuity to the earth for some reason?
 
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