Car running wierd and throwing p1500 and p0505 code

[Shwillbo00]

i just bought this car a week ago...drove it back home 110 miles and right when i got infront of my house the check engine light came on. i got my own obd2 reader and scanned it..its throwing a p1500(alternater fr terminal malfunction) code and a p0505(idle control Sensor) code.. the p0505 im not worried about but the p1500 code on the other hand...im pretty good with engines and ive owned and worked on a few dsms...ive also been looking on here about the p1500 code and i realize it could either be my alternater, the wiring from the alt. to the brain or the brain itself. My car runs and rides fine but idles at like 900-1000 rpms and sumtimes jump to about 1400- 1500 rpms and then back down to 900...it doesnt act like it wants to die...just idles really wierd..last night i checked the 4 pin connecter on the alt. to make sure it was plugged in and im sure it was...i know luv2rallye has obviously ran into this problem before so hopefully he can better explain this problem to me...any help will be very highly appreciated!!!

 

[Shwillbo00]

You have an open circuit either inside the alternator (FR terminal, pin 4, green wire) or a bad connection (open circuit) from this terminal to pin 41 of the ECU (could even be the ECU, but least likely). Check this 4 pin connector first. Then measure voltage on pin 4 while turning headlights on - voltage should drop. The ECU uses this signal to control idle speed when heavy electrical loads are turned on.

ive checked the green wire on the 4 pin plug and i get like 11.08 volts from it...if you turn the head lights on it drops to 9.08 something. So obviously the wiring is good right?

theirfor do i need to get a new alternater or is my ecu bad?

hopefully someone can help me i just spent $3,800 on this car two weeks ago and its already starting to crap out on me

 

[the_mork]

Check the alternator output or pull it off and go get it bench tested. I would doubt the the ecu is at fault.

 

[98GSXtreme07]

Your P0505 code would be your ISC. I get this code every once in a while. If you still have the tan one, known to fail more, than I would go ahead and purchase one of the new one's (they're black). Make sure to reset your ECU when you do this. Now as for your altenator, you can bring it to Autozone or the likes and have them test it for free for you.

Where to purchase, and learn a little, the newer ISC's: DSMISC Automotive (New ISC Supplier)

 

[Shwillbo00]

Went to the local O'riellys and they said alt. and battery is good...where should i go from here?
I got another 40-50 miles maybe to see if the cel comes back on. If it does throw the same code at me(p1500)...should i just go ahead and replace the alt. anyway O'rielys offers a reman. one for $140.00 with lifetime warranty...they said they cant get me a NEW one....Or would it be my ecu is going bad. My car runs and rides fun...kinda misses here and there but shes due for a good tune up to...so with that said how could my ecu be going bad? and if my alt is good why does the car keep throw the p1500 code at me...ive checked for continuity from end to end of the green wire from the 4 pin plug on the alt to pin 41 on the ecu and its fine. Thanks for your help fellas!!

 

[cisco5311]

If your alternator was bad you most likely wouldn't be aable to drive your car over 10-15 miles on a fresh battery. I would make sure that the connection on the altenator is clean and also clean your battery posts.

If your altenator was bad you would be able to start and drive the car but once you drained the power from you battery the altenator would no longer be replenishing it and your car would die out.

You could also check the accessory belt that runs the altenator to see if it tight enough and is not severly worn, causing it to slip and not rotate the alt.

Hope this helps

 

[blktalonawd]

I had a similar problem and it ended up being the alternator relay had an issue. I opened the relay up and it looked normal but a new one fixed it. Also there could be a problem with the internal regulator having too much resistance but charges just fine. Also the po505 is probably not just a bad isc, it throw this code for the correlation between the tps and base idle settings. You need to verify that the tps is set right and the cars base idle is set right. Check to make sure that the CTP or closed throttle position switch is operating properly. It is a simple on or off check with a scan tool, it should be correlated in the tps. If the ctp is found to be bad a new 4 wire tps for your car is needed.

 

[luv2rallye]

The green wire pin 4 (FR terminal) is a signal line to the ECU which indicates the alternator's output (or load). The ECU uses it to control the idle air control motor according to the alternator output. This prevents the idle speed from dropping at times such as when the headlights are turned on.
P1500 means this alternator output signal is not working properly or a bad ECU. It's nearly always the alt. This signal is NOT checked by ANY auto store tester (a shop that repairs alts is the only one that might) so your alt will always test fine there. Recommend getting a new alt. Or taking it to a shop that repairs alts/starters and having it tested there - they also sell far better rebuilt alts than any auto store.

 

[Shwillbo00]

Thanks fellas....

Ended up buying a new bat., alternater, and belt and so far were good on the p1500...im gonna go and get a new isc this friday and hopefully thatll fix my problem with the p0505 code.

Thanks 4 your help!!

 

[U2_slow]

http://www.dsmtuners.com/forums/problem-diagnosis/317796-check-engine-light.html

http://www.dsmtuners.com/forums/problem-diagnosis/318487-p0505-new-isc-next-step.html

 

[tjbiker031]

when i had a problem with my ISC, i just adjusted the BISS and the p0505 code went away. just something to think about before spending all that money one a new ISC.

 

[spyderturbo007]

You can give this a shot.

If that doesn't work, this is the cheapest place to pick up a new one.

 

[4G63dsm1]

I'm having the same problem with code P1500. I replaced the battery and alternator not too long ago and i started having that code along with code P1400 (MAP SENSOR)...I wonder if code P1500 is linked to code P1400, Does anyone knows? This is my second alternator i go thru, My first one made my battery lights staying on almost all the time. Autozone Alternators suck!!

 

[spydermangst97]

I'm having the same problem with code P1500. I replaced the battery and alternator not too long ago and i started having that code along with code P1400 (MAP SENSOR)...I wonder if code P1500 is linked to code P1400, Does anyone knows? This is my second alternator i go thru, My first one made my battery lights staying on almost all the time. Autozone Alternators suck!!

I have the same problem and work at autozone and tried three diff alts from different stores but nothing helps. You may have another issue

 

[spydermangst97]

Its the ALT. My alt as well as many other REBUILDS tested fine on the bench tester but wont charge the battery on the car. Replace with a new or used OEM. Every rebuild from motion and napa that I tried did the same thing. I paid 35 for a used one off craigslist and solved all my problems!

 

[Eagle_Phoenix]

FIRST OF ALL YOU MUST CHARGE YOUR BATTERY 100% BEFORE BEGIN THIS DIAGNOSES, I SAW ON YOUR PREVIOUS POST THAT YOUR BATERY WAS FALLING? CHARGE IT FULL FIRST BEFORE DOING ANY DIAGNOSE.

Ok, regarding the first error code P0505, are you experiencing idle problems? This code may be the ISC or the wiring to it, this sensor controls the air flow allowed to the own amount of air needed to stabilize the pro engine idling, this is a quite strong part to burn, I got some 2G dsm with wiring broken straight on terminal, also with a very high oxidation in it, I don't know why it get so much oxidation on harness and socket of this sensor.

FULL TEST OF ISC (IDLE AIR CONTROL MOTOR)

For you to test the resistance of ISC you will need a multimiter and a long piece simple wire of 2 meters basically, using ohms selection on multimiter, connect one point of the multimiter on pin 2 and the other point on pin 1 and after that on pin three of IAC socket, the multimiter should read 28 to 33 ohms in each case, if not, the ISC has a open coil and definitely you must order a new one from somewhere.

Now, if you got the normal resistance in this step, then go to the step two, connect one multimiter point on pin 5 and the other end on four and six, again should show 28 to 33 ohms, if not also the ISC will have an open circuit on coil and you must replace it for a new\used working one.

TESTING THE WIRES BETWEEN YOUR ISC AND ECU

After this diagnose, if your ISC is alright, you must check the wiring from your ISC to your ECU, if your multimiter has a beep selection, choose it, remove the harness from ISC, remove the two screws on driver side cover where is located the ECU, take a look on pins 4,5,17 and 18 on ECU all comes from ISC, then you must get a long wire fit it on ISC harness contact to every colour you want to test on ECU, then go to the ECU and connect one point of the multimiter on point of this wire and the another multimiter point into the colour pin of ECU you connected the long wire on ISC harness and it must have full resistance and you hear the beep after connecting the another multimiter point into 4,5,17 and 18 pin on ECU depending on what pin contact you choose on IAC harness, do you know what I mean?

This will give you a full 100% the wires are in perfect condition if you don't find resistance on colours, make sure it is connected properly the contact of the long wire to the ISC harness, if everything is properly connected, then you must hunt your wire brake or blown on colour that is not beeping or giving resistance.

Let me see now, you tested the ISC and the wire link between the ECU and ISC, if all this tests were fine and nothing wrong, then your ECU definitely has a problem, if you understand a little bit of electronic, you can try to open your ECU and chasing what components firstly has near the 4,5,17 and 18 pin on ECU, I did repaired twice this Blondie ECU replacing and making a custom ECU a 5 years ago on my lancer I had on time, because there was not a ECU for it on Brazil and I found a similar motherboard circuit without using some parts, so I got the same board but missing some micro-capacitors, diodes, micro-transistors and fuses with a different EEPROM firmware in it, and of course it was not starting up my car, then I installed a socket, removed the old EEPROM, removed my old EEPROM from my broken ECU, ordered a new chip for it, then using a universal EEPROM reader, I read the file on old EEPROM, saved to a file on computer, installed the new EEPROM in it after clearing it with a ultra-violet laser fluorescent lamp, put it back to car and it was working like a just born babe! But this is another history ....

Regarding this P1500 ERROR CODE,

You must check the wire from alternator if it links straight to Generator FR Terminal on ECU pin 41, it is a green wire on ECU socket, now you can use my same method before, using a multimiter with beep and ohms selection if possible, disconnect the FR Terminal from alternator and put this wire in it, go to the ECU pin out and on one hand you close contact with one point of multimiter terminal and the another point you put on terminal 41, IT MUST HAVE A BEEP AND A 100% RESISTENCE LINK or your wire is broken and you must find where is broken or replace this wire.

If this wire is ok, then the problem is on your Alternator, you could remove it, open it and test the diodes, check rotor brushes if it is not fully spent, but this will be another day help you.

Now, how the FR terminal works, I will write a book now, the Generator FR Terminal is responsible for turn on and off the field in the alternator injection module in response to this signal; the injection module senses the load and controls the output amperage according to the load consumption of the vehicle.
This prevents the car to idling variations that can be caused due an overload of the circuit.

Generator generates load when the power transistor feeding a load on the alternator field, when the power transistor turns off, the load generated by the alternator rapidly decreases.
The size of the load of the alternator depends on the amount on which the power transistor is turned on (range 0% to 100%).
The voltage on the FR is low when the power transistor is switched on and high when power transistor turned off.

However, the (range 0% to 100%) of the power transistor voltage regulator or the output current from the alternator can be felt when calculating the voltage FR terminal is low.

When the alternator reaches the regulated voltage (Approx. 14.4 volts) the voltage regulator switches the transistor on to off. When the output voltage falls below the regulated voltage, the voltage regulator switches the power transistor from off to on, this way the battery is kept charged constantly.

I hope I could help you, please tell me if it does work and rate me!

Bye for now.

 

[estoyaqui30]

I guess I'll bring this thread back to life. I'm having a problem with P1500 codes and I followed the procedures as described in the factory manual, so I'm thinking that it's the alternator. I checked the battery and have 12.5 VDC, I connected a voltmeter to the green wire (pin 4) at the alternator and I get between 7 and 8 VDC with the engine idling and no extra load. If I turn on the lights, wipers, defroster, etc, the voltage goes down. I checked the continuity of the FR wire from the alternator to the connector at the ECU (pin 41) and I am getting 0.18 ohms....I take that as a good wire. I'm thinking it's time for a new alternator again!? These alternators just don't seem to last very long. This one has been in for a year, maybe 2. This one is a Mitsu reman, the last one was from alterstart and It lasted less than 1 year. Has anyone seen or thought about a way to "remote" the regulator and electronics, get them away from the heat of the turbo, downpipe, etc?

 

[luv2rallye]

Sounds like you need a new alt alright. You should get around 14.4v at the battery with nothing on. The voltage you're seeing on the green wire with varying loads is normal however. Make sure the PS unit is not dripping oil onto the alt - it kills alts very quickly and is a typical reason.

 

[Shuey1]

I guess I'll bring this thread back to life. I'm having a problem with P1500 codes and I followed the procedures as described in the factory manual, so I'm thinking that it's the alternator. I checked the battery and have 12.5 VDC, I connected a voltmeter to the green wire (pin 4) at the alternator and I get between 7 and 8 VDC with the engine idling and no extra load. If I turn on the lights, wipers, defroster, etc, the voltage goes down. I checked the continuity of the FR wire from the alternator to the connector at the ECU (pin 41) and I am getting 0.18 ohms....I take that as a good wire. I'm thinking it's time for a new alternator again!? These alternators just don't seem to last very long. This one has been in for a year, maybe 2. This one is a Mitsu reman, the last one was from alterstart and It lasted less than 1 year. Has anyone seen or thought about a way to "remote" the regulator and electronics, get them away from the heat of the turbo, downpipe, etc?

Quick questions on this test.

I checked my FR wire by disconnecting the 4 pin harness from the alt. I check the FR wire and had no voltage. I had a reading at other 3 wires, battery voltage with ignition on, and also with engine running with a .5 voltage drop.

On the FR wire is there suppose to be voltage from the ECU to the Alt. or the Alt. to the ECU?

Should I have the connector plugged into the Alt. and probe the FR wire?

The Alt. is not charging the battery. I replace the battery, the old one tested good, but with the constant charging and draining it didn't seem to hold a charge long so I replaced it to rule it out. The alt is a reman from Nappa. Belts good. Fuse link good. Grounds all have been cleaned.

I went through 2 alts. from Autozone both of those tested bad in car and on bench after I removed them. They tested a 3rd one they had in stock and it failed bench test right out the box. so I wen t to Nappa and put in the one that's in it now yesterday. This started about 2 weeks ago. It's a 02 eclipse 4cyl. No electrical mods all stock.

 

[luv2rallye]

Assuming your 3g is the same alt wiring as the 2g...the green FR wire is a sense line which supplies voltage from the ECU and has a voltage divider sense circuit in the ECU. It's voltage varies with alt load so it's voltage can be anything (does not indicate charging so ignore it).

If the alt does not get at least 8v on the L terminal (either blue or black-yellow wire) it will not put out. This can be due to a burned out dash charge light. The S terminal (red) must also have at least 8v to work.

Also make sure you have exhaust mani heat shield on or the alt can burn out. Also will burn out if PS is leaking on the alt.

 

[Shuey1]

Assuming your 3g is the same alt wiring as the 2g...the green FR wire is a sense line which supplies voltage from the ECU and has a voltage divider sense circuit in the ECU. It's voltage varies with alt load so it's voltage can be anything (does not indicate charging so ignore it).

If the alt does not get at least 8v on the L terminal (either blue or black-yellow wire) it will not put out. This can be due to a burned out dash charge light. The S terminal (red) must also have at least 8v to work.

Also make sure you have exhaust mani heat shield on or the alt can burn out. Also will burn out if PS is leaking on the alt.

Ok great, yeah the wiring on it is the basicly same as the 2g. Colors are different but positions are all the same as my 99. (checked wiring diagram)

One other thing I noticed, my battery light does not come on when ign is in "on" when it is not charging correctly, when the light does come with the ign. in "on" posittion the car charges correctly 14.4v. Does the light actually affect charging? If it is not working does that really make it not charge?

Since I get nothing on the Fr that won't cause it not to charge then? I do have 12v or so on the S wire and the L wire so I am good there. I do have the same 12v on the G wire, with it unplug and on, That's not a problem is it?

So I take it all with the car is good, sounds like I got another bad alt....

Thanks for your help!!!


Thanks for the advice got it fixed with another alt. 3 bad ones from autozone and 1 bad one from Nappa, 2nd Nappa one worked!!!! What a pain!!!
I do appreciate all the advice in this thread.

 

[luv2rallye]

You don't know how many hundreds of times I hear on here (and people pm me) about getting bad alts from auto stores especially Autozone.

 

[luv2rallye]

Does the light actually affect charging? If it is not working does that really make it not charge?

Since I get nothing on the Fr that won't cause it not to charge then? I do have 12v or so on the S wire and the L wire so I am good there. I do have the same 12v on the G wire, with it unplug and on, That's not a problem is it?

YES if the charge light is not working the alt won't put out. Pre 3g they had a "generator relay" which was a backup to the charge light not working - but it was deleted on 3g.

0v on FR is actually an indication of it not working properly. On my 99 I get 8.8v on FR at idle with nothing else on. It goes lower with more loads added (eg. headlights on, etc).
12v on G is ok.

 

[NJresident]

I'm new to the forum, I have a 1995 talon tsi fwd(gst) and I also have code p0505 that I jus got recently, before the code my car would idle low at stop but in movement the car was fine, also while aproaching a stop, right before coming to a complete hault the car would jerk a little while the idle lowers a lot then comes back up but the car does not stall out, I adjusted the screw on the throttle body and raised the idle to where it shuld be, or at least to where I think it should be(1000rpm) at idle, after a week I get the code(p0505) car still lowers idle sometimes, still no stalling out, still jerks sometimes when coming to a stop, doesn't really feel like the iac, could it be that the throttle body is really dirty? Needs a good cleaning? That is one of the probable causes on that code, also between the intercoolr pipe and throttle body(where these 2 meet) is a little moist like the gasket between them is bad, if anyone could guide me in the direction id apreciate it, thanks

 

[NJresident]

i cleaned throttle body, did the gaskets, cleaned map sensor, cleared the code, car stoped jerking at stops, idled better, drove smoother all for a good hour and a half....then engine light came back on again, same p0505 code, car drives a little better tho but still jerks once in a while coming to a hault(stop) and this morning while on my way to work i let the car warm up to op temp and when i hit 40mph the rpms shot up and car loss gear, then a sec or 2 later caught gear again and drove normal...im confused should i change iac/isc? or tps? even tho tps code is p0120 i believe...i dont want my car to die