Bizarre electrical problem...
Thread Starter
Racer
Joined: Nov 2002
Posts: 471
Likes: 0
From: Queens NY
Bizarre electrical problem...
OK hopefully someone will be able to explain this....
I hook my scanner up to the cig lighter and to the ALDL, and I get the right readins half the time, and wacky numbers the other half
oh, and when i shut the ignition off, it still shows the last read value instead of 'NO DATA' like it should
Then I power the scanner by a separate battery instead of the cig lighter, and i get 'NO DATA' which basically means no connection at all
Any ideas??
I hook my scanner up to the cig lighter and to the ALDL, and I get the right readins half the time, and wacky numbers the other half
oh, and when i shut the ignition off, it still shows the last read value instead of 'NO DATA' like it should
Then I power the scanner by a separate battery instead of the cig lighter, and i get 'NO DATA' which basically means no connection at all
Any ideas??
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
Re: Bizarre electrical problem... (CarAteMyMoney)
When you use a separate battery to power the scanner and get , "No Data", this is a symptom that the ground connection on the ALDL is open. If the ground is open, your scanner should work ok when you power it up with the cig lighter.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
Re: Bizarre electrical problem... (CarAteMyMoney)
Looking into the ALDL connector under your dash, the top right pin is ground and you can verify this with an ohmeter. The schematic shows this pin goes to engine ground but there is no description where.
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From: North Yorkshire, England
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Re: Bizarre electrical problem... (jfb)
Sometimes the ALDL pins become loose in the connector and will push out when inserting a diagnostic connector. I like to put my finger behind the ALDL when I push the diagnostic connector in so I can see if any pins a pushing out. The ground pin seems to be the first to loosen. If it does want to push out and not make connection with your diagnostic connector, pull the ground pin and if the locking tang is still there, try bending it out a but so it will lock.
Thread Starter
Racer
Joined: Nov 2002
Posts: 471
Likes: 0
From: Queens NY
Re: Bizarre electrical problem... (Ray Quayle)
ok, i went under there with a multi meter before and it showed no continuity between the black ALDL ground wire and any other ground... seems like this is my problem, but would it also cause the car to run like crap?
my guess is yes, if the other grounds are messed up too.. i guess my next step is to trace that ground.. or just splice a new one in..
anyone else have any thoughts?
EDIT: ALDL ground and ECM ground both have no continuity to any other ground, yet they have continuity with each other.. looks like the harness is coming apart tomorrow!!
[Modified by CarAteMyMoney, 10:10 PM 5/19/2003]
my guess is yes, if the other grounds are messed up too.. i guess my next step is to trace that ground.. or just splice a new one in..
anyone else have any thoughts?
EDIT: ALDL ground and ECM ground both have no continuity to any other ground, yet they have continuity with each other.. looks like the harness is coming apart tomorrow!!
[Modified by CarAteMyMoney, 10:10 PM 5/19/2003]
Advanced
Joined: Apr 2002
Posts: 62
Likes: 0
From: Hopkinsville Ky
Re: Bizarre electrical problem... (CarAteMyMoney)
Ifalldata is correct because I don't have an '86 manual,your ALDL ground is
part of a major ground for ECM and MAF,it is G104,it is located below LH valve
cover at rear of engine,but ground circuit for ALDL has connectorC237 behind
RS of I/P,near dash grommet,so if car runs ok then you probably have prob-
lem at that connection
part of a major ground for ECM and MAF,it is G104,it is located below LH valve
cover at rear of engine,but ground circuit for ALDL has connectorC237 behind
RS of I/P,near dash grommet,so if car runs ok then you probably have prob-
lem at that connection
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Thread Starter
Racer
Joined: Nov 2002
Posts: 471
Likes: 0
From: Queens NY
Re: Bizarre electrical problem... (jfb)
yeah, that's what Mitchell's says.. it says that the ECM, ALDL, MAF, and Fuel pump relay ALL use the same ground
now, the mass air ground has continuity to other grounds.. BUT the ECM and ALDL don't... so im guessing there's a split in the wire between those two, and the MAF/FP... would that make sense? :banghead:
now, the mass air ground has continuity to other grounds.. BUT the ECM and ALDL don't... so im guessing there's a split in the wire between those two, and the MAF/FP... would that make sense? :banghead:
