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I just bought my '85 a few months ago and since then I've been trying to address all of the repairs one by one and I've finally got around to the radiator fan. A previous owner had it wired direct so if the ignition switch was on the fan was on. Not the best but at least I had a fan to prevent overheating. A few weeks ago I installed a new radio and it was working fine. Then suddenly it would not work and neither would the fan. When I put the radio in the ignition switched power wire had 12 volts. Now when I check the voltage it has only shows 1.6v. Where did my voltage go? The wiring around the fan relay and behind the radio is a cobbled up tangle of wires that I cannot make heads or tails of. Please help!
Thanks confab, but no it doesn't help. I have a shop manual but am too dumb to understand the wiring diagrams. I should have mentioned that I bench tested both the fan motor and the relay and they're both working.
There are a few guys on here that are good with wiring. I'm one of them.If you can take GOOD pics of the wiring at the relays (separate the wires so colors and position in the connectors show up) and post them, or even describe the location and colors of wires that are cut or damaged, we may be able to suggest a remedy.
Another thought is for you to ask questions about the function of the wires (by color) in a circuit. Research online how and why relays are used in automotive circuits. (Basically a remote-controlled switch that allows a device to control a high current that it can not control directly because it would burn up).
In the wiring diagram, the relay is on the left. The "switch" part of the relay is on the left. The relay "coil" is on the right. When current flows through the coil, it closes the contacts in the switch. The dotted line is the mechanical interface between the coil and contacts.
Red = Hot at all times. Battery voltage supply to the fan.
Blk.Red = Output to the fan. (When the contacts close, the fan is powered on).
Dk Blu = Hot in RUN. (Power for the coil is only available with the key in RUN. In any other position the coil can not be energized, so the fan can not run either).
DkGrn/Wht = Control for the coil. Ground this wire, the coil will energize closing the contacts IF the key is in RUN. Note there are two possibilities to ground the coil and turn on the fan. The ECM, OR the "override switch" in the head. Both can be grounded at the same time. Either one can turn on the fan. The intent is that the switch in the head will turn on the fan if the electronic controls (ECM) fail.
Thanks confab, but no it doesn't help. I have a shop manual but am too dumb to understand the wiring diagrams. I should have mentioned that I bench tested both the fan motor and the relay and they're both working.
IHBD is right. To do this stuff yourself and to do it safely, it would be good to at least get some basic theory down.
You can start a fire messing with wiring if you don't know what is what. In fact, it sounds like the PO's fix may have failed for this reason - Something was overloaded and burned up.
I would suggest either doing what IHBD said and posting pics and we can help, or paying to have it done right.
If you have ever experienced an electrical failure/fire, it happens very quickly and it does great damage in a hurry. It's not something to skimp on.
Wow. Thanks for all of the tips. Looks like I have a lot to do. I've been scratching my head so much it is raw. lol. I'm going to take a break tomorrow and play golf then hit it again Thursday. There is one other thing I forgot to mention and that is that the genius that did this has ran a hot wire that bypasses the relay completely. It comes through the firewall beside the steering column.
It may take me a day or two to get back to you. I've got about 5 miles of electrical tape to get off.
Get a cheap multi meter from harbor freight and a test light, and then we can help.
If you're doing something once or twice, the cheap HF multimeters are fine. If on the other than if you're doing or expect to do more in the future, consider something a little better. Most meters will read volts and ohms via the probes. Some are capable of utilizing a snap-on loop the check dc voltage without puncturing wiring etc. Typically all you need to do is snap it around a wire to check. Note: many can only read ac voltage this way while others can read ac and dc voltage this way. I was taught this earlier this year and picked one up, I have not used it a lot but it sure is convenient the few times I did to confirm whether a wire was hot or not.
If you're doing something once or twice, the cheap HF multimeters are fine. If on the other than if you're doing or expect to do more in the future, consider something a little better. Most meters will read volts and ohms via the probes. Some are capable of utilizing a snap-on loop the check dc voltage without puncturing wiring etc. Typically all you need to do is snap it around a wire to check. Note: many can only read ac voltage this way while others can read ac and dc voltage this way. I was taught this earlier this year and picked one up, I have not used it a lot but it sure is convenient the few times I did to confirm whether a wire was hot or not.
If you're doing something once or twice, the cheap HF multimeters are fine. If on the other than if you're doing or expect to do more in the future, consider something a little better. Most meters will read volts and ohms via the probes. Some are capable of utilizing a snap-on loop the check dc voltage without puncturing wiring etc. Typically all you need to do is snap it around a wire to check. Note: many can only read ac voltage this way while others can read ac and dc voltage this way. I was taught this earlier this year and picked one up, I have not used it a lot but it sure is convenient the few times I did to confirm whether a wire was hot or not.
Yeah, I've got that same meter just for the clamp on thing.. I thought it quit working when I was doing load calcs on the kitchen, but the led bulbs didn't draw enough current to register. (The halogens they replaced sure did!)
If you use an A/C clamp on meter remember to break out the hot wire and only measure it. If you try to measure say an extension cord it will show 0 amps even if current is flowing through the wires. The current through the hot and neutral cancel each other out on the meter.
I am back finally. Here is what I know now. The fan motor is good. The coolant temp sender is new. The blue wire is hot when the ignition switch is on. Grounding the green wire closes the relay. Still no fan. I have noticed that the red wire is in the 4th position in the harness plug but there is no lug for it to connect to on the relay. I hope you can see what I am talking about in my bad pics. What
gives?
Looks like wrong relay or incorrectly wired connector, best I can tell. According to some online catalogs there is an early and a late 85 cooling fan relay, not certain how different they are.
That connector has been seriously overheated. As a minimum, clean up those contacts with some fine wet-or-dry sandpaper to make them shine! Your analysis that the pins don't match is a very good reason for the fan not to operate!
Check the voltage on pins C and D (pin A is on the left in this picture). Pin D should always have 12 v. on it. Pin C should have 12 v. only when the ign. is on. A little di-electric grease on the contacts would be a good idea to prevent oxidation. Your favorite parts store should have this for light bulb sockets.
OP - there's much going on in that snapshot you posted. A quick glance looks as if maybe a fusible link is compromised with a poor repair. The connector condition is questionable so I'd think I'd do a correct relay, a connector and sort all of the wiring in the vicinity of the battery and cables.
Make sure the relay you purchase is the equivalent of a GM 10038311 and the connector required to mate to it a Pico 5648PT should be available locally I'd think and likely $8 or so, there's other options that might be a few $$ more. If there's little or no insulation shrinkage maybe you just unpin the existing wires from your old connector and insert in the new connector.
Whatever that is in the snapshot that's obviously a cut/splice and tape needs to be confirmed as good.
The fusible links for cooling fans for '85 are off a positive cable pigtail from the battery.
If there's little or no insulation shrinkage maybe you just unpin the existing wires from your old connector and insert in the new connector.
If you're going to buy a new connector (probably a good idea), I'd suggest using the new complete connector, rather than re-pinning the new connector body with your old pins. Those old pins are distorted, dirty, and probably damaged from overheating, and may be difficult to remove from the connector body without further damage. Be sure to use good splicing techniques (soldered, no crimp connections), and insulate with heat shrink sleeving.
09-26-2017, 11:17 AM
Wiring expert needed badly!
