padgett Posted January 17, 2019 Share Posted January 17, 2019 OK having a problem with the 88 cooling fans. Have identified the relay main power (pin 30) has voltage that goes away as soon as the relay engages. This indicates a bad fusible link A or a bad feed wire to the Underhood Relay Center. So I look in the 88 (89 also) service manual for how to remove and it refers to section 6D5 page 3. Ok except I have 6d5-1 and 6d5-2 but no 6d5-3. In either manual. Is there any trick to removing the Underhood Relay Center to examine the feed wires ? Thought I'd ask here before just removing bolts. Link to comment Share on other sites More sharing options...
2seater Posted January 18, 2019 Share Posted January 18, 2019 I just remove the torx head through bolts/screws in the relay block and it comes loose. If memory serves there are two that recess into the socket block between relays. Link to comment Share on other sites More sharing options...
DAVES89 Posted January 18, 2019 Share Posted January 18, 2019 2seater is right... Link to comment Share on other sites More sharing options...
padgett Posted January 18, 2019 Author Share Posted January 18, 2019 Thank you, thought it was simple but you never know. Link to comment Share on other sites More sharing options...
Barney Eaton Posted January 18, 2019 Share Posted January 18, 2019 Padgett........you are correct about the pages not being in the Service Manual..... not in 1991.......but in the 1988 final edition, there is a 6D5-1 and -2 but it does not show the relay box Link to comment Share on other sites More sharing options...
padgett Posted January 19, 2019 Author Share Posted January 19, 2019 6D5-3 is not in 88 or 89 FSM, just appears in the index. Link to comment Share on other sites More sharing options...
padgett Posted January 26, 2019 Author Share Posted January 26, 2019 (edited) Hooboy. Have pulled the relay center out. The red feed wires for the fans have 9v until they get a load then it goes to zilch so have either a bad connection, bad fusible link A. Or a bad wire. The problem is *which* wire. The feeds are all red coming from the main power source by the battery. Many red wires go back. Many red wires go down. Anyone know how to tell which is the fan main power when the connection is bad but all look good ? Do the go around the back of the engine or under the front ? Everywhere I look there are big red wires. ps there are three individual red wires, one to each of the relays in the relay center. I *suspect* they all join into a single larger wire to the feed by the battery. Anyone know where that connection is ? Edited January 26, 2019 by padgett (see edit history) Link to comment Share on other sites More sharing options...
Barney Eaton Posted January 26, 2019 Share Posted January 26, 2019 (edited) Don't know if this helps.....it is a scan from the 1989 service manual Sorry that is difficult to read and is not the relays..........try this Edited January 26, 2019 by Barney Eaton (see edit history) Link to comment Share on other sites More sharing options...
padgett Posted January 26, 2019 Author Share Posted January 26, 2019 Thank you. I "suspect" the issue is either fusible link A or splice S106 but trying to figure out which of about 20 different red wires in two bundles (one shown) most with fusible links. Is not trivial. Particularly when there is a known issue so may not be able to just ohm out. Going to try to find the splice first. Link to comment Share on other sites More sharing options...
Ronnie Posted January 26, 2019 Share Posted January 26, 2019 Does the blower motor for the heat run like it should? Check the orange wire that supplies power to the blower module for 12 volts under load. If it is good the fusible link is good. As you can see in the photo that orange wire comes straight off fusible link A that supplies power to the cooling fan relays. The photo is from an '89 but I think it would be the same for an '88. Link to comment Share on other sites More sharing options...
padgett Posted January 26, 2019 Author Share Posted January 26, 2019 Thanks for the tip and heater fan is not working properly so probably the fusible link A. Blem Wit is WHICH fusible link is A ? Have at least five coming off the terminal by the battery. For the moment so I can go to the cruise tonight I have run a 14 ga wire with a 30A fuse directly to the S106 splice. This has the engine cooling fans working. Suppose can do an ohms check to the terminal block but have enough working for tonight's cruise. 1 Link to comment Share on other sites More sharing options...
Ronnie Posted January 26, 2019 Share Posted January 26, 2019 7 hours ago, padgett said: Thank you. I "suspect" the issue is either fusible link A or splice S106 but trying to figure out which of about 20 different red wires in two bundles (one shown) most with fusible links. Is not trivial. Particularly when there is a known issue so may not be able to just ohm out. Going to try to find the splice first. I see an orange wire in that bundle of wires. If it ties in with a red wire coming out of a fusible link that is probably fusible link A. You could try testing the fusible link by piercing the wire with a straight pin and use that as a test point to apply a load (12 volt light bulb) to see if the problem is a bad fusible link or a bad connection downstream somewhere... Link to comment Share on other sites More sharing options...
padgett Posted January 27, 2019 Author Share Posted January 27, 2019 That is my next thought, the splice which has no name at the fusible link. Would explain why the blower fan is not backfilling from my new feed at S-106. Link to comment Share on other sites More sharing options...
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