Chevy engine keeps running in off postion

JerryD · May 06, 2008, 03:36:37 PM

Hi,Got a small wiring problem? 84 GMC motorhome will NOT stop running when switch is turned Off,Still has fire to the dist,Works just fine in off/on/acc position Until you start it then have to remove battery cable to kill the engine ANY One ever run into this? Where to start looking ,Any help appreciated,Thanks Hopefully JerryD

EMSjunkie · May 06, 2008, 03:56:53 PM

Yep. do a search, I think there is a diode or something you need to put between the dizzy and the ignition switch, I think :?

I know it has been discussed before, just not sure when

Vance

JerryD · May 06, 2008, 04:09:14 PM

Quote from: "EMSjunkie"Yep. do a search, I think there is a diode or something you need to put between the dizzy and the ignition switch, I think :?

I know it has been discussed before, just not sure when

Vance

Ah now to find out 'when',because seems is feeding back from the alt,or something,It belongs to a friend and He says just started doing it,while sitting parked,as said the switch works like it should unitl the engine is fired then even in off positiong keeps running and the current stays on the fuse panel,,,,,as well as to the distributor,

EMSjunkie · May 06, 2008, 04:47:37 PM

maybe that is where the diode goes, between the alt and the dizzy.......
I know someone will chime in that has a better remembery than me :oops:
I tried to do a search, but came up emptyhanded

where is Enjenjo when ya need him

:!:

Vance

MrMopar64 · May 06, 2008, 04:53:12 PM

Make sure the wires on the starter are tight....
Had an Impala do this and the small wire on the starter had come loose and had moved and was touching the battery cable terminal on the starter
Of course we started at the switch :oops: Took us awhile to find it

MM64

GPster · May 06, 2008, 06:48:29 PM

I'd take a guess that it's in the ignition switch. A diode was my first thought but if it was feeding from the alternator the it wouldn't make any difference if the battery was hooked up. If that's the way he gets it to die then I'd think that the power is going to the battery like it's supposed to. Maybe I should have waited til tomorrow to find out but it's just a guess. Fat Cat is the motor home expert. Maybe it's something even further out. GPster

Dave · May 06, 2008, 06:56:55 PM

If its got an electric fan check that too.. It still could be the alternator also. I had both issues and my roadster runs till the fan stops

Ya its on my list but ive been riding the bike and hell with the hot rod

Well that and cleaning the shed and garage .. Time to toss stuff..
Dave

wayne petty · May 06, 2008, 07:04:13 PM

from alternator shops .... WAI part number 46-1873 Adapter Plug
For: Delco 10SI Series IR/EF Alternators
Used On: AMC
Replaces: AMC 8128393, Ref. No. S-3300
Notes: Anti-Feed Back Harness for 10SI equipped AMC. Eliminates ignition feed back.

now that you know where the diode is... i wonder which way it faces...

almost any alternator shop will be able to get this....

Bob C · May 07, 2008, 10:09:13 AM

If the ignition wire is on the "on" terminal on the ignition switch it will keep running. Move it to the "acc" side to seperate the ignition from the alternator.
Bob

An electric fan will do the same if it's not on the acc terminal.

Dave · May 07, 2008, 10:19:48 AM

the acc terminal is for tha radio and stuff when you need power and the ignition is off. The distributor should be on the ign terminal and the fan can run from there also as well as the wire to energize the alternator but if you dont have a diode in line then feed back from fan and alternator can make the car run and not shut off. a relay would work as well. I could cure the problem on my car by just moving the fan to the battery terminal but i wanted it off when i turned the engine off.. a lot of the newer cars i thought used to let the fan run till the temp switch shut em off i dunno if they still do ..
Dave

Bob C · May 07, 2008, 11:23:10 AM

Quote from: "jusjunk"the acc terminal is for tha radio and stuff when you need power and the ignition is off. The distributor should be on the ign terminal and the fan can run from there also as well as the wire to energize the alternator but if you dont have a diode in line then feed back from fan and alternator can make the car run and not shut off. a relay would work as well. I could cure the problem on my car by just moving the fan to the battery terminal but i wanted it off when i turned the engine off.. a lot of the newer cars i thought used to let the fan run till the temp switch shut em off i dunno if they still do ..
Dave

I didn't word that right. What I meant to say is don't have anything on the ign. terminal that could cause feedback from the alt. likean elect. fan

Dave · May 07, 2008, 11:29:17 AM

Quote from: "Bob C"
Quote from: "jusjunk"the acc terminal is for tha radio and stuff when you need power and the ignition is off. The distributor should be on the ign terminal and the fan can run from there also as well as the wire to energize the alternator but if you dont have a diode in line then feed back from fan and alternator can make the car run and not shut off. a relay would work as well. I could cure the problem on my car by just moving the fan to the battery terminal but i wanted it off when i turned the engine off.. a lot of the newer cars i thought used to let the fan run till the temp switch shut em off i dunno if they still do ..
Dave

I didn't word that right. What I meant to say is don't have anything on the ign. terminal that could cause feedback from the alt. likean elect. fan

Well assuming its stock wiring for the vehicle then id look for a problem within that wiring. Can you find a schematic? Most anything can be figured out but i wont touch a wiring problem on a vehicle without a schematic. It just isnt worth the trouble.. At this point im thinking there is a relay in the harness somewhere that is stuck closed or for some reason has voltage on it all the time to hold it closed when it shouldnt.
Dave

wayne petty · May 07, 2008, 07:49:29 PM

if the motor home uses a chevy truck dash this is the link to the wiring diagrams..

http://www.autozone.com/az/cds/en_us/0900823d/80/11/56/bb/0900823d801156bb/repairInfoPages.htm

figures 9 and 10 cover the 84 model...

being a motorhome there may be a lot of differnt additions to the electrical system...

UGLY OLDS · May 07, 2008, 08:43:59 PM

Hey Guys...All good idea's BUT I think we're getting away from the core problem... :? This motorhome USED to work properly...Something has gone wrong with the ORIGINAL electrical system.. The diode in the alternator wiring works because WE put it there on vehicles we wire...I never had to install one on a factory wiring loom....

Jerry...Get online & go after the schematic for the CONVERSION part of the vehicles wiring ...At some point you will find where it ( The motor home portion) picks up power from the chassis wiring...Hopefully they just pull power from the starter solenoid or someplace else close to the battery... See if you can isolate the motor home feed from the chassis wiring ....This almost sounds like a relay in the MOTORHOME wiring that is sticking closed & backfeeding the alternator....REMEMBER :!: :!: It worked properly before & nothing was changed or rewired ...I have seen this countless times on limos that are "rewired" as part on the conversion...The original "taillight warranty" operation ...Trust me ...

Wish I could be of more help....

Bob.....

enjenjo · May 07, 2008, 09:00:36 PM

Does this happen to have a battery isolator?