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I Purchased this car with hopes to fix an issue a previous mechanic gave up on. From my diagnosis here’s what I have:
- When I connect the battery the cars ignition acts as if it’s in the ACC position, the digital readout on the dash is on (all indicators lit) The information panel is on (most indicators are lit) and all interior courtesy lights are illuminated
-on more than one occasion I’ve turned the dial down to off on the dimmer and all the courtesy lights went off, so did the digital readout on the dash,Park and brake indicators stayed lit & the info. Panel stayed lit.
-SYS Light is Flashing
-Security Light On constant
-Battery voltage at last check was at 11.43v
-Car reads about 9v
-Obd scan seems to not be talking to the car computer
-digital readout on dash for fuel,oil,cool has no info
Steps???
ive only been able to peek at the ground on the drivers kick panel, a tad bit corroded but not loose
Vats Issue? If so ignition switch also which makes the car think it’s turned to on
PCM/BCM Issue? The car interiors electronics are out of whack so they aren’t talkin too the engine electronics, which points back to vats?
I really hope hope you guys can help point me in the right direction I know it’s a bit much but I’m at my wit end and haven’t the foggiest idea where to start. I just know I’ve always wanted this car thanks
Do you know the history of this car? Have you been able to get a CarFax report? Does the car have a clear title, or is it a "salvage" title? I see that you're in New Orleans. Is there a possibility this is a flood damaged car?
Do you know the history of this car? Have you been able to get a CarFax report? Does the car have a clear title, or is it a "salvage" title? I see that you're in New Orleans. Is there a possibility this is a flood damaged car?
hey thanks, yes I do have the car fax I would be the third listed owner of the car. Normal routine maintenance throughout its life here and there. No accidents. the vehicle was purchased and spent most of its life 80 miles from here, it is a clear title. And previous owner assured its never been under water. The old guy said one day it just stalled out and he hasn’t been able to get it started since. I found the car posted for sale dirt cheap so I figure what the heck. They guy listed that he had dismantled the dash in an attempt to hunt down the electrical issue. Now here we are dash still disassembled, everything still connected, just going haywire.
I went out out to try to pull the dash lcd readout/flash codes but now the dash display isn’t displaying anything. Only the park and brake indicators. To make matters worst when I press the horn button, the key in ignition chime and sealtbelt indicator come on.
the car does have some serious weather striping wear but the car was kept under a carport and there is no signs of interior damage from water. Just dryrotten and brittle
im prepared to hunt down and swap wiring harnesses and electronic components if need be. Just not sure where I should start.
You're well beyond any normal diagnosis and into "parts car" territory.
If you're experienced enough with cars to fix this, then nobody here is going to have any wisdom that you don't already have.
I'd start with cleaning every ground and unplugging / replugging every electrical connector. Those may or may not fix it, but in so doing you'll see everything electrical in the car and maybe you'll find the problems.
Have you thought about the actual ignition switch? It connects from the cylinder to the switch by a rod. If that's out-of-whack I assume you might see what you're experiencing. Just a thought.\
Also, you will want the FSM as there are a lot of diagnostics in there.
I now have my hands on a haynes manual for now until I can get my hands on a fsm
new update from further diagnosis
I’ve just located the ignition switch on the steering column ad it does look a bit funky but I’m not sure how I can go about testing it so the plan is to get a new one
ive literally removed the entire dash frame now with the entire interior wiring harness exposed
with power connected I began moving and shuffling wires and I’ve found that touching the ccm to a metal surface activates the dash cluster, door chime, interior lighting. Basically back to where I was before the dimmer switch incident mentioned above.
If Im not mistake the ccm is grounded by the center dash support. Correct?
What would cause the dimmer switch to gain. Control of these functions?
are they grounded on the same circuit, or powered?
this time I was able to pull codes and it threw back a few which I plan on lookin up soon
that being said the car is still not responding to a key turn
I now have my hands on a haynes manual for now until I can get my hands on a fsm
new update from further diagnosis
I’ve just located the ignition switch on the steering column ad it does look a bit funky but I’m not sure how I can go about testing it so the plan is to get a new one
ive literally removed the entire dash frame now with the entire interior wiring harness exposed
with power connected I began moving and shuffling wires and I’ve found that touching the ccm to a metal surface activates the dash cluster, door chime, interior lighting. Basically back to where I was before the dimmer switch incident mentioned above.
If Im not mistake the ccm is grounded by the center dash support. Correct?
What would cause the dimmer switch to gain. Control of these functions?
are they grounded on the same circuit, or powered?
this time I was able to pull codes and it threw back a few which I plan on lookin up soon
that being said the car is still not responding to a key turn
You have a body ground that's missing, or otherwise damaged.
Last edited by PatternDayTrader; 07-19-2018 at 07:07 AM.
Ok that sheds some type of light on my situation I’ll go check the grounds in a moment thanks I think I’ll that with the ones on the back of the engine block
Ok that sheds some type of light on my situation I’ll go check the grounds in a moment thanks I think I’ll that with the ones on the back of the engine block
What is most likely to be happening is that the circuits which seem to be effected, are providing a ground path for other circuts. So it appears as though there is this major electrical problem and a short between circuits, when really all that's wrong is the proper ground path is open.
Ok so today I checked and cleaned the frame rail, side of engine block, and also fuse able link connections. No change
it would really help I I could find the interior harness wiring diagrams. Maybe I could trace down the ignition circuit to the problem. I’m thinking it has to be a problem somewhere between the interior light circuit and ignition circuit. Maybe something in either of those circuits shorted out
You will be doing yourself a huge favor by grabbing the 94 field service manuals...all the wiring diagrams and countless troubleshooting flowcharts will be in them. When I was fighting an electrical problem with my ASR/ASB the FSM's led me to a bad EBTCM. It would taken me forever to figure out with out the FSM! The Haynes manuals are awful for dealing with this kind of stuff!
Fsm manual ordered
new update:
started unplugging stuff of the passenger side in an attempt to narrow down the dashes/ignition switch source.
found that disconnecting this junction disconnects the dash readout and, false key turn issue.
from there I was able to trace leads back to the fuse box, long story short now with fuse #37 LH CTSY removed the ignition cylinder works as it should Cycling through all options from lock to run.
from here plan is to find out why the CTSY light circuit cause the ignition to think its on
PS: CTSY LIGHTS stay on all the time unless both courtesy light fused are removed (LH&RH)
ALSO could anyone tell me where this connector goes it has leads from fuse box
fuse number
#17 Valet
#33 Ecm
is there some module that this terminal connected too?
Fsm manual ordered
new update:
started unplugging stuff of the passenger side in an attempt to narrow down the dashes/ignition switch source.
found that disconnecting this junction disconnects the dash readout and, false key turn issue.
from there I was able to trace leads back to the fuse box, long story short now with fuse #37 LH CTSY removed the ignition cylinder works as it should Cycling through all options from lock to run.
from here plan is to find out why the CTSY light circuit cause the ignition to think its on
PS: CTSY LIGHTS stay on all the time unless both courtesy light fused are removed (LH&RH)
It sounds like your courtesy light circuit is finding a ground path through the instrument cluster, making everything light up. You need a wiring schematic. Something both the courtesy lights and the instrument cluster have in common is the dimmer switch. You might try putting everything back together and just disconnect the dimmer switch and see if everything returns to normal.
Last edited by PatternDayTrader; 07-20-2018 at 09:40 PM.
While I wait for the fsm to come in I thought I’d take a whack at the dtc codes
dtc 41 is first to come up and the worst
followed by
c72
&
c74
both which are triggered because the radio isn’t installed
And of course err on module 4 because there is no input from the pcm
now besides all the threads available on dtc 41 does anyone have any info on 94 & up dtc 41 errors. Because, all those threads are for 93 and lower and seems as if these guys were able to buy new eprom/memcal chips (which goes into a slot on the bottom of the ecm) problem is these chips in the 94 are different and I can’t seem to find anything on this year model car with that error.
While I wait for the fsm to come in I thought I’d take a whack at the dtc codes
dtc 41 is first to come up and the worst
followed by
c72
&
c74
both which are triggered because the radio isn’t installed
And of course err on module 4 because there is no input from the pcm
now besides all the threads available on dtc 41 does anyone have any info on 94 & up dtc 41 errors. Because, all those threads are for 93 and lower and seems as if these guys were able to buy new eprom/memcal chips (which goes into a slot on the bottom of the ecm) problem is these chips in the 94 are different and I can’t seem to find anything on this year model car with that error.
A better place to search for specific questions like this is camaroz28.com. It's a mostly-dead forum today, but the archives are very valuable.
Ok thanks I will check them out also, but my vehicle in question is a 94 therefore c41 is a
ECM Serial Data Circuit failure
I have my fsm now and I’ve been tracing down circuits to find that there is no continuity between the ccm and the ecm serial data lines now it’s on to finding out why
07-17-2018, 12:20 AM
Please Help 94 C4 Electrical Gremlin
Seems like the most likely cause.
