Where is the Left side actuator relay?

[KLUTZ]

I have found the three of them and isolated the driver side relay. What I'm doing:

Doing some electrical tracing on my '87 Vette and I'm trying to figure out why the driver side headlight pod isn't getting power. The headlight goes on, but the bucket won't move. I checked for power at the connector to the motor and get nothing. There is no issue with the passenger side. I am looking at the wiring diagram in the Haynes but since all the wires are harnessed.
I have now checked the relays and they are fine. On the driver side, I am getting power to the yellow wire at the relay but still not getting power to the connector for the pod. I am checking the green wire for power. (none at the grey or black of course) There isn't a long distance from the relay to the connector and it's wrapped with original hard plastic wrap. Is there a fuse in there that is not showing on the Haynes diagram or could the green wire somehow be damaged under there? Am I looking in the wrong spot?

 

[KLUTZ]

Hummm.. Ok I have power to the red and yellow on the wiring going to the passenger side relay, but only power on the yellow wire going to the drive side pod. It sounds like there must be a fuseable link in there somewhere but where? Could I tap into the red going to the passenger relay and operate both or would that overload the circuit? Or should I start searching for an interrupt in the red wire?

 

[boomdriver]

Hummm.. Ok I have power to the red and yellow on the wiring going to the passenger side relay, but only power on the yellow wire going to the drive side pod. It sounds like there must be a fuseable link in there somewhere but where? Could I tap into the red going to the passenger relay and operate both or would that overload the circuit? Or should I start searching for an interrupt in the red wire?

Ok...I doubt the Haynes manual is going to help. Its vague, innacurate and as generic as toast. Most useful under a table leg. I have one. I forget where I threw it after too many projects that were disasters because of poor detail, bad info, improper process and just plain vague descriptions of the work. Search here to locate the link for new FSM on disc or in print. E-Bay has used sets for all yr models. One book is nothing but electrical drawings and trouble shooting the systems.

There 3 relays are NOT wired as you might think.
One is a "master" of sorts. The next is for left side. The 3rd is rt side BUT its thru one of the others. I'd have to get the FSM elect book out and review the drawings.

There will be 2 relays that are alike, 1 that is different. Swap the 2 like relays and see if the problem moves. They are cheap. Just isolate the bad one. ....in fact, thats what one is called, the "isolation relay".

Let me see if I can scan the drawing (s) and attach them. Or I can scan the flow chart that gives detail on the test. These motors/gears fail. Not uncommon at all. BUT, its rare that a motor fails...usually gears or relays. The motor itself seems to be quite durable.
If you have the time/money many folks upgrade to later yr headlite drives due to easier rebuild,. cheaper repair and better reliability.
I'll get back to you with the FSM details.

 

[KLUTZ]

Thanks Boom. I have a FSM on the way already. Should be here this week I hope. The relays are all fine and the motor is good on the one that won't operate. I plugged the driver side headlight pod feed into the passenger side relay, with the feed from the passenger side, and it went up. As I mentioned, I have only power on the yellow lead to the relay and not yellow and red as with the passenger side one. I'll take a good look at what you scan and post up here, if you can. Back to work tomorrow so it'll be all reading for the next three days, no hands on.
And I agree 100% with your thoughts on the Haynes manual. The one for MGB's is similar, very vague. Forms like these are the only way to work these days, without a factory manual...

Paul

 

[boomdriver]

You should be able to pin it down with this. IF the motor seems to be faulty,. replacement of a single must be of the same model motor. You CAN upgrade to 89+ and up, but it requires both motors with a different control system. A harness that does not use relays. You can replace a single 87 motor for about $150. Sometimes as low as $75 if you buy a used one, salvage dealer etc. Lots of rebuilders. Back to $150 exchange for that. Again, search E-Bay for actuators when you;re shopping for FSMs. If you open the motor case, be forwarned, its much more complex than it first appears...the armeture shaft is under spring tension, the shaft acts as a torque switch that moves each way to trip limit switches that absolutely must be adjusted properly for everything to work right. Its .....delicate, for lack of a better word right now. If you don;t mess with the motor the gears are easy to change. But, there is no need to open the motor case unless its absolutely necessary.
Good luck.

 

[KLUTZ]

Wonderful. Thankyou so much...

 

[boomdriver]

If the motor went up and operated by switching relays, its a relay. Probably the isolation relay. See drawing. It has more to do with one side than the other.

I survived 20 yrs without a FSM for my several C4s. I learned MORE in one month after getting a FSM than I had in the previous 20 yrs....the detail and instruction is priceless. They cover every possible issue and teach you the hows and whys. The flow charts walk you thru every diagnostic there is. Well worth the cost with more efficient time spent and money saved on un-needed parts purchases.
Good Luck

 

[KLUTZ]

If the motor went up and operated by switching relays, its a relay. Probably the isolation relay. See drawing. It has more to do with one side than the other.

The driver side motor went up when I plugged THAT side into the relay to/from the passenger side. And I did the opposite with the passenger side. No work. That is why I am thinking that the fusable link on the red wire to the driver side is faulty. It says something about "Heavy duty cooling fan" but half of it is cut off. Where does this red wire with the fusible link come from and where could I find it to check? Again, both relays work on the passenger side headlight pod.


Just saw the location on the "Headlight Doors" page. Fusible Link F... LH rear of engine compartment, behind battery. I'm on it tomorrow.

 

[boomdriver]

ALL circuits that have fusable links originate on the "jumper post" behind the battery. Most links are behind the battery, under the tray and cannot be easily seen without removing the battery and tray. Remove the body side panel by loosening the lower 10mm bolt, loosen the upper 10mm and then remove the several torx along the wheel well edge. Panel comes off to access the battery and other mysteries of the Corvette electrical system.

If there is no power to the rust/red hot wire (L HL door power) then test at the jumper for power.

The HD cooling fan is the 2nd fan ( aka the aux fan) thats in front of the condensor. Can be seen if you look into the nose from in front of the car. If there is no fan there.....its the standard cooling package with only the big puller/sucker fan on the engine side of the radiator.. The HD fan will also have a relay mounted on the left side radiator shroud near the headlite actuator. No HD fan....no relay up there. Because they share a power source, the L headlite actuator would die IF the HD fan shorted or jammed with debris and caused the link to melt. GM links are readily available at any parts store. They sell them by the wire size. 14g....16g etc
To prove the link is bad, jump power from the jumper post to the relay. Thats likely in the diagnostic flow chart. Its covered in there.