LS1GTO.com Forums banner

1 - 20 of 22 Posts

·
Registered
Joined
·
10 Posts
Discussion Starter #1 (Edited)
My car is in storage . As such I was looking for a way to ‘prime’ the engine when I started it once every 2 months .
Some Moron on YouTube said press the throttle down fully when turning the key and the injectors will not feed fuel . If you do this you don’t need to pull the fuel relay out when priming the engine. I would turn key for about 10-15 seconds to get oil up and then take foot off throttle, and then start car .
It was during these starts that the ABS alarm , and Service Soon messages came on . I did it a few times before I said I don’t like the sound of this . So, I stopped doing it .
The car A/C started to misbehave after this time .The A/C started to work sometimes and not work others . I had it regressed but it has gas . It was working before I did this stupid throttle down trick . I got a new pressure switch as guy said it was that but that was a waste of money . I bought climate control unit and it made no difference. I swapped relays no difference . I checked earth connections , no difference. The compressor works and starts when you turn it on but then shuts after a few seconds. I lived without A/C .

Then one day I have the “Tail Light Globe” error message. I disconnected battery for 2 mins and it went away. A few weeks later the ABS warning came on while driving.

Now ABS beeps, Instruments cluster dies and the radio goes off. It’s scary but the car still drives fine other than electrical blackout and incessant beeping .Then the car returns to normal.

A 10km drive would get 2-3 alarms. It started to be every time I drive it, I got ABS alarm.

I tried the TPS reset, disconnect ECU fuse, turn engine to on, pressed pedal 5 times, then put fuse in. I did this and the A/c worked once. I have done it since and still no a/c. It sort of seems linked because sometime a/c compressor will stay on for a few seconds more before disconnecting.
I am really struggling here buying parts and nothing changes.
I then borrowed an ABS unit from another friends identical car (and yes it had doing full throttle starting when priming too) . When I changed ABS unit, the car ran fine for about a week with NO ABS alarms.
Now the car is doing it again with the second ABS unit. Less frequently like once a day on way to work and once on way back (10km drive) a/c still didn’t work .

I sent the ABS to a guy who fixes them and he says there was nothing wrong with it and the fault must be somewhere else in the car .

So, I stopped driving the car because I started new job just before Covid 19 and so couldn’t come to new job stressed about car ABS alarms.
Does anyone have ideas ?
OBD2 scan images shown below
501442
 

·
Worthless reject member
Joined
·
40,376 Posts
The timing of the throttle trick you did and your issues appearing is probably just coincidence.

Did you check the a/c system pressure?

As far as the ABS faults, they sound like they are from serial communication dropping out. Happens from a few issues, low system voltage, a component on the serial bus that is failing, and could even be an issue with the harness.

How is the system voltage when the car is running?

Oh, and after a quick check of the wiring diags, the PIM seems to be the link for serial data to the EBCM, intrument cluster, and radio. Something else worth checking.

Other module failures are possible, but less likely. BCM and ECM could be at fault, but if the ECM runs the engine, it is likely fine.

Checking the harness is worth your time. I do not know if RHD models have the same harness chafing issues we have here, but it is possible.
 

·
Registered
Joined
·
10 Posts
Discussion Starter #3
Hi , a/c pressure is good as i had it regassed and the car a/c did randomly work for 20mins at a time . I forgot to add the battery is new 600amp battery as they has been a problem in other peoples issues.
Voltage is 13.4 as i have a digital battery gauge that goes in 12v socket .
I did notice that one historic error was high Volatge and that old battery died recently when i hasd it in another old spare car .

What else causes the serial communication drop out.?

What does -a component on the serial bus that is failing?

thanks again.
 

·
GR-RRR!
Joined
·
5,663 Posts
Have you checked your BCM wires?

 

·
Worthless reject member
Joined
·
40,376 Posts
I edited my post above with new info.

13.4 seems low, but is still fairly normal. May just be system load or the voltage drop since you are reading it from the outlet. You may want to have someone watch the voltage as you drive. It also seems that you have some type of scantool, if it reads live data or can log data, would be worth doing.

Not sure i understand your question about the serial bus.
 

·
Registered
Joined
·
10 Posts
Discussion Starter #6

this link sounds like my car. maybe alternator and regulator is no good?
 

·
Registered
Joined
·
379 Posts
Like someone already said, the throttle trick simply puts the car in de-flooding mode and has nothing to do with your problems. I also use that to prime the engine if it's been a few months since I last started it.

Check for loose or bad wire from the alternator. My father's car (not a GTO) recently had a similar issue where all kinds of lights were flickering on and off and was getting high and low voltage from the alternator. It turned out it was a bad wire from the voltage regulator or something.
 

·
Registered
Joined
·
10 Posts
Discussion Starter #8
gto.jpg



Hi i made a mistake the alternator makes 14.4 volts at idle. Yes i have heard that a bad connection can cause issues , i will have a look on weekend. thanks for comment .
 

·
Worthless reject member
Joined
·
40,376 Posts
I would data log if you can. If there is a sudden, intermiddant drop in voltage it should catch it.

Then again, there is the chance that the drop in serial data would affect that, so having someone watch the voltage as you drive would work as well.

Depending on your ECM and alternator type, your regulator may be self regulated or ecm controlled, btw.

If it is a voltage regulation issue, is possible that if you have an RVC alternator and that if the connections check out, it could be the ECM or the alternator circuitry.
 

·
Registered
Joined
·
300 Posts
The timing of the throttle trick you did and your issues appearing is probably just coincidence.

Did you check the a/c system pressure?

As far as the ABS faults, they sound like they are from serial communication dropping out. Happens from a few issues, low system voltage, a component on the serial bus that is failing, and could even be an issue with the harness.

How is the system voltage when the car is running?

Oh, and after a quick check of the wiring diags, the PIM seems to be the link for serial data to the EBCM, intrument cluster, and radio. Something else worth checking.

Other module failures are possible, but less likely. BCM and ECM could be at fault, but if the ECM runs the engine, it is likely fine.

Checking the harness is worth your time. I do not know if RHD models have the same harness chafing issues we have here, but it is possible.
The PCM is the translator, the BCM is OBD 1, ECM (as you know) is OBD 2
 

·
Registered
Joined
·
10 Posts
Discussion Starter #11
SOLUTION
Hi guys the car just did the ABS alarm thing. My voltmeter read 17 VOLTS !
i switched off and then started car and it was 11.7 volts .
I revved it a few times and it went to 13.7 volts.
i have ordered a new alternator .

Thanks for you help though guys .I had to eliminate options till i got to this one.
Regards
L
 

·
Registered
Joined
·
379 Posts
SOLUTION
Hi guys the car just did the ABS alarm thing. My voltmeter read 17 VOLTS !
i switched off and then started car and it was 11.7 volts .
I revved it a few times and it went to 13.7 volts.
i have ordered a new alternator .

Thanks for you help though guys .I had to eliminate options till i got to this one.
Regards
L
I am pretty sure it is not your alternator that is the problem. Did you check for bad wires to and from the voltage regulator? Follow the wires that plug into your alternator from the alternator itself to wherever they go and make sure they are not bad on either end or anywhere in the middle. These exact symptoms (with voltage spikes to high voltages and low voltage readings) are exactly what I had an experience with on a different car recently and changing the alternator made no difference (even made it worse after fiddling with the wires while changing it). It was the wires that plug into it that were bad all that was needed was a wire repair.
 

·
Registered
Joined
·
10 Posts
Discussion Starter #14
OMG! tonight on my way home from Work the Alternator spiked to 18.9 VOLTS! a ridiculous record i expect. I pulled over and switched off and then switched on but it sat on 11.5 volts for about 10 mins before switching bck to 13.6 volts . I have bought a new Bosch alternator and will change over - if i get any more problems after i will contact you guys.
 

·
Worthless reject member
Joined
·
40,376 Posts
hopefully that fixes your issue. if it does not, let us know what year/model you have. our cars here in the us came with either a normal internally regulated alternator that uses a sense wire, or an RVC alternator that interacts with the ECM for on/off and duty cycle. it would help to further diagnose if we knew what kind you had.
 

·
Registered
Joined
·
379 Posts
Hi where were the connections that you replaced ?
Sorry for the late response. I had to check with my father because it was on his car and he ended up taking it to a mechanic after I changed his alternator and the problem had not gone away, even got worse. From what I understand, because I was not there and did not speak to the mechanic, it was the wires for the regulator but I guess on the side where they plug into a control module, not sure what module exactly, and it was a different car so it wouldn't be helpful to you anyway. But like I was saying before, if I was trying to figure it out on my car, I would follow the wires from the alternator to wherever they lead and check for any cuts/loose connections anywhere along the path.

What I think is happening, especially for the high voltage spikes, is that a wire which reports output of the alternator or battery voltage has a cut or bad connection somewhere and when the connection gets completely or nearly open at times, it requests maximum output from the alternator because it thinks the battery voltage/alternator output is very low. So the alternator responds with maximum output and spikes the voltage up to very high values. Then, when the connection gets restored, the control module responds with an opposite extreme, commanding a very low output from the alternator. It's hard for me to provide more details because I don't have wiring diagrams available to know what the connections for the alternator actually are. Does anyone have access to any wiring diagrams they could share? I technically have repair manuals for the GTO which may have that, but I don't have them in my house right now.
 

·
Registered
Joined
·
10 Posts
Discussion Starter #18
502102
502103
502104
502105


Ok guys, i changed the alternator for a Bosch. I think its the overrun type as it spins differently in one direction. The old one hadresistance both ways. No burnt smells or noisy bearings. Too early to say after 1 day . But i will tell you after a week or so if it is ok or NFG. A/C still not working.
 

·
Worthless reject member
Joined
·
40,376 Posts
thanks for the pics. it definitely looks like you have the older style alternator. US cars with the same style alternator have a white and tan wire that connect to the alternator. white wire is a DC sense wire for the regulator for voltage control, which comes from the battery, and the tan wire comes from the cluster and is for the warning lamp and serves as the field wire.
 

·
Registered
Joined
·
1 Posts
thanks for the pics. it definitely looks like you have the older style alternator. US cars with the same style alternator have a white and tan wire that connect to the alternator. white wire is a DC sense wire for the regulator for voltage control, which comes from the battery, and the tan wire comes from the cluster and is for the warning lamp and serves as the field wire.
View attachment 502102 View attachment 502103 View attachment 502104 View attachment 502105

Ok guys, i changed the alternator for a Bosch. I think its the overrun type as it spins differently in one direction. The old one hadresistance both ways. No burnt smells or noisy bearings. Too early to say after 1 day . But i will tell you after a week or so if it is ok or NFG. A/C still not working.

First time poster so forgive me if I meet up somewhere but I wanted to let everyone know I have had a similar issue on my 04 GTO that has taken me over a year to resolve. Originally it started after I filled my tank up with gas one night and after starting I got an alarm that said abs error, gas gauge error, air bag error, tcs was off, a/c shut off and told me to see dealer for service or something of that nature. It first Started out on hot days then eventually It was all of the time. I changed the bcm out with A new bcm from Rock Auto but did not help. I traced bcm wires for chaffing and found no issue. I finally just Continued to drive it being it drove fine. I did find one day when under the hood that I could unplug the abs module with the car running and the Ac switch in the on position, I could unplug the abs module and plug it back in and the ac would blow cold as long as the car was running but once it was off, I would have to unplug And plug back in the abs module if I wanted ac. After a year of doing this, i decided to send in my abs module just to see if that was my issue. i Also had tried hooking a Tech 2 up but I wasn’t able to communicate with any of the modules, but when I unplugged the abs module and hooked up the tech 2, It was able to communicate and verify there were no errors with the ecm, bcm, or pim. I sent the abs module in to cheapabs For repair and found that was my whole issue all along. I have searched forum after forum and never found a solution. Several say it’s speed sensors, bad cluster, etc. but mine was the abs module.
 
1 - 20 of 22 Posts
Top