Yamae

Thanks for the report, csalazar87. Another happy owner! Many other members will be encouraged by your report.
Congratulations on your success to fix problems not only the gas mileage but also the bigger torque and the power. Enjoy the road trip to Connecticut with your girl friend.

csalazar87

Hi guys!

Just as an update, I ran a full tank test and achieved a total of 378 for the tank or roughly 19 MPG in my 1992 SC400.

The test was around 200 miles or so of Highway and the rest was local.

Thanks again!

csalazar87

Hey Yamae, so I wanted to perform the big 3 upgrade and I tried to change the OEM negative battery terminal and add extra ground points.

Now my battery is not properly charging [around 10.5 v] Or at all.

1.The car was functioning perfectly before
2.battery is new
3.alternator + power steering about 12 months ago


I simply changed both negative and positive terminals and didn't expect so much trouble from the car.

Abs and Trac light comes on as voltage drops below 9.0 volts while engine is on . I jump started from another car and restored the voltage back to around 12.5v [Trac and abs turned off] but as soon as I removed the jumper cable...voltage would drop back down to 9.0V.

I added a negative terminal cable from the auto part store [precrimped 4 gauge copper lead lead]

I brushed the paint off of the ground connection next to the battery.
I measured the resistance of the cable before installation, it was 0.01 ohms.
after installation I measured from the negative terminal to chassis ground and it was 0.02 [which I hear is bad].

I am 99% sure I have grounded the negative terminal correctly. I suspect that I may have fractured or disconnected a the negative wire lead from the harness due to stress from stretching the wire to the negative terminal of the battery.

Anyway, I'm out of ideas...I plan on checkIng the remaining ground connections and also positive terminal connections [I. E. Alternator and any suggestions ].

Please let me know of any continuity tests or other test procedures in order to narrow down the problem if possible

Thanks in advance

Yamae

Hi, csalazar87. I strongly suggest you to use a genuine battery cable with a post to avoid the galvanic problem. Many people don't know how it is important. After-market ones often cause serious problems because of the lack of considerations of galvanic series.

A metal to anther metal contact is a big theme of our industries. You need to study hard to make good and safe products. Some people buy some after-market cables without knowing galvanic issues and often face serious problems. I find many educated people even don't know the fact.

Search the net with keywords "galvanic" "contacts" "metal to metal" and yo will know more.

Once many American houses had fire risks and actual problems which were caused by the galvanic corrosion, we must remember. May be we still need to pay attentions.
http://abihomeservices.com/aluminum-...anch-circuits/

I also suggest you to check the wirings between the alternator and the battery. The alternator should generate around 14.4V at the +B terminal of it while running the engine 1500rpm with conditions tail lights off and on. The voltage change should be less than 0.2V except the ripple. If it drops more or too low, it simply means that the alternator is not fully OK.

csalazar87

OK so I did a few things

1. I replaced the terminals with the original terminals, inspected all ground points and deoxidized
2. Performed continuity test from +batt to +alt. the voltage read 12.0v from both points so no voltage drop .
3. I jump started the car and read voltages from +batt and +alt and they both were decreasing at the same rate.

Conclusion: bad alternator [verified at autozone as well]

I just wonder why the alternator died at the same time that I changed the battery terminal. Or was it a bad ground connection??or did i somehow accidently short out the alternator?

The alternator was dirty however from most likely the PS pump...and the copper wire was black and looked burnt.

So I replaced the alternator and everything resumed back to normal operations. Phew

Legender

So now you need to change out the PS pump if you've not already done so. Known fact that leaking PS pumps will kill the alternator. I just replaced the PS pump on mine after it killed the alternator before I bought it. Alternator will fail again if you don't get that leaking PS pump fixed.

clamsoup

which capacitors do I need for sc400? thanks in advance~!

DK Audio

Thank you for creating this thread. I'm trying to read the whole thing but am only on page 20 so far. Hopefully this will help someone with a 98.

I have a 98 LS400 with 150K. I have some symptoms such as...
-Speedometer sometimes stays at 0.
-Low RPM idle at a stop while in drive, makes the car pulsate and shake.
-Check engine light, catalytic efficiency below threshold, 02 sensors checked out good.
-AC compressor doesn't kick on (just started getting nice out here), had a leak but thought it was fixed.

I opened up the engine control module and the board looked great. Note that mine was just 1 circuit board with no ribbons as mentioned in post 1. Picture is below with the cap values and voltages I found in RED, they did match up with LS in post 1. There were two non Nichicon caps. One was a big 330uf 35V high reliability, the other was a 47uf 25V high reliability. The Nichicon caps that I found where (from top to bottom left to right in the pic)...
47uf 63V
47uf 63V
10uf 50V
10uf 50V
47uf 63V
100uf 10V
220uf 16V
100uf 10V
33uf 35V

When I put the ECM back in (yes I unhooked my negative battery terminal) I let the key in run for about a minute and then started the car. It idled LOW, sometimes down to 250rpm, car was not smooth. Like I said, my caps and board looked great but I am going to give this a try, will order the caps from post 1. These are all through hole right? I know the board is multi layer but these caps go all the way through I assume.

cobalt91

The thing is the ecu is usually the last thing that is checked in the trouble shooting process. I assume you are still able to pull codes from your ecu. Can you post these codes so we can better help you with this issue.

DAT9LEX6

Just went theough all 74 pages and noone has my problem.

I have a 96 ls400 with the 89661-50303 ecu and it fried a transistor. Is it fixable and if so how do i go about getting the transistors value?

Also would the transistor plus caps cause these codes?
P0110 iat sensor 1 circuit
P0325 knock sensor 1 circuit
P0330 knock sensor 2 circuit
P1300 igniter circuit
P1305 igniter circuit bank 2

dicer

I have a stupid question. What is the SIMPLE procedure for ordering the capacitors? Can I call an outfit and say "I need the caps for a gen 1 LS400" and they will know what to send ? I will want enough to do 5 ecu's and then maybe spares too.

Yamae

Thanks for reading whole 74 pages, DAT9LEX6. I can see how you are eager to fix your problem.

First of all, it's not easy to fix even for a skilled guy because there is no information available at all. You need to do a kind of reverse engineering. I always do so as a hobby not for a job.

Your problem seems to be totally different from the capacitor issue. I sometimes encounter fried transistors and fix most of those but those will fry again if I don't find the root cause of those and fix those before that. For an example, when a drive transistor for an IACV was fried, you also need to check an IACV. Most of the case, it's short circuited internally. So you need to replace both the transistor and the IACV.

Regarding the name of a transistor, see other transistors near by. Find one which has exactly the same size and shape and read the name. Then confirm that the transistor matches the load. The same transistors are often used for the similar purpose. Some times you need to assume only analysing the load. I mean to check the voltage, current, speed and transient spikes. For an example, if it's a solenoid driver, use a transistor which is capable for it.

Hope your success.

RA40

iTrader: (6)

Once you have the values for the parts needed from the first page, calling Digi Key or checking the web site is probably the way to go. Not sure of the available quantities so in that instance a call for any cross reference parts would be next.

Supraman24

for some reason i can't open page 75..

Cowboy, quick question. Yamae mentioned that after it should be "coated" with something after completing the work. Do you know what we can purchase here in the states for this "coating" Yamae was unsure what we could use here.

Thanks!

sha4000

iTrader: (1)

Posts were most likely deleted in the thread but the page count stays the same.