inhibitor/choke relay causing alternator problems???

[wivrrat]

Hi.  Having a unusual problem with my 83 z24 engine.  Lately I have been hearing a chattering noise coming from the passenger side of the truck, under the glove box.  A Couple times when the chattering was happening, the alternator light came on.  Twice I opened the hood and lifted the negative cable off the battery and the engine died.  Most of the time when this occured I was driving down or up my long dirt canyon drive (slow speed).  Once I hit pavement and sped up, the alternator light went out and the chattering stopped.  

I finally took it to a alternator shop yesterday and they removed the alternator and it looked brand new and tested fine.  I told them about the relays I found chattering and they looked it up on a scamatic.  Identified them as the choke relay and inhibitor relay.  The inhibitor relay (larger one) was the one doing the chattering.  I felt it when it was chattering and it was hot to the touch and the relay was constantly connecting.. 

I asked the mechanic how these relays could be affecting the alternator and they didn't know.  He said the description of the inhibitor relay said it was to be used on a automatic transmission vehicle?????

I haven't removed the relays yet as I planned on doing that this a.m.  I'm thinking of just replacing the relay if I can find it.   Went to 4 auto parts stores and none showed a inhibitor relay.  All had the choke relay. 

I hear that relay engaging everytime I turn the key on in the ignition.  Do remember in the past when the truck set for a long time and the battery was low and I tried to turn it over, I heard the chattering in the lower right corner.  Seems to be influenced by the battery voltage????

Any suggestions from the forum would be greatly appreciated.  Thx, Bill

[Justin Berni]

I have the same problem except for me it's the smaller one, the choke relay, that makes a noise. Mike told me it's probably because my alternator isn't working 100%, I havnt messed with mine yet tho..

[wivrrat]

I finally looked at the relay and called a couple parts stores and the relay is around $50.00.  Don't understand why the truck has the relay when I don't have a intank pump?

[datzenmike]

1/ The inhibit relay only prevents starting in any gear but PARK and NEUTRALin an automatic equipped vehicle, so forget it.

 

 

2/ Choke relay needs full alternator output or charge, to power the choke heater and warm and keep it off when running. The relay doesn't affect the alternator... it's the other way around. I would check the easy stuff that you can do yourself. Battery cables clean and tight? Alternator wires clean and tight, two wire plug pushed in snug? Belt tension ok?

 

If new looking it's likely a cheap $60 repop like Bosh. They can test good or bad right out of the box but are equally bad.

 

Had no idea those relays were $50 but I grab them from junk yards and have dozens of them.

 

 

3/ There is also a fuel pump relay but unlikely this is whats making the noise. It also needs alternator output to keep the electric fuel pump running. This doesn't seem to be in your description though.

 

 

 

Everything points to low or no charge at low /idle speeds. Tighten belt?

[bryant2482]

sounds like the alternaor is going out

[datzenmike]

Or loose wire? Seems charge related though

[xsdg]

Easy test: Have truck off.  Measure battery voltage.  Start motor, idle, measure battery voltage.

 

For a properly functioning electrical system, battery voltage with engine off will be slightly above 12V, and battery voltage with engine on will be slightly above 14V

 

 

Another easy test: check the voltage across the solenoid intake lines with the truck running.  Does this match the hopefully 14V that you see across the battery?  If not, that could indicate high resistance in the line that feeds the solenoid, which could also cause a voltage drop to the point where the voltage at the solenoid is right around the threshold voltage.

[wivrrat]

Hi.  Have been doing some further research.  Turns out it is the intank pump relay that was chattering, relay #28545-89900, not the inhibitor relay as the mechanic told me.  The relay, as King Rat said,  has to do with the fuel pump.  It provides power to the external fuel pump located on the side of the truck, and if it goes bad, you will have no power going to the fuel pump.  As to the alternator, I had it taken out and bench tested.  Tested fine.  I will be looking at battery cables, belts, etc. as suggested in the other posts and do some testing.   Sure have a lot of problems with the electric on this truck.   May need to take it to a electric shop and have it gone over.  Thanks for the replies.

[datzenmike]

Cheaper to come here.

 

Check the wrecking yards for another one. Also bone up on the fuel pump relay here for fixing tips...  http://dlarson.hubpages.com/hub/The-Datsun-and-Nissan-Pickup-Fuel-Pump-Relay-What-the-Haynes-Automotive-Repair-Manual-Wont-Tell-You