Baffled, need help if possible

[Glider]

Hi all,

I purchased 1995 M plate, LS400 about 6 months ago as a project, as it hadnt ran for 3 years, it was garaged though, it wouldnt start so I had to have the immobilizer bypassed, and a new Battery, it then started first time, then MOT passed with just a number plate light out, which they sorted for me. I drove down the road feeling like a king never had I been in such a smooth quiet car, amazing. previous best car was my 7 series beamer loved that too, but, this just felt better to drive.

First job 4 new tyres, balanced and tracked.Next timing belt water pump and pulleys, then a new altenator as it failed and a service on the power steering pump, I then started to get a strange thing happening after start up from cold, I pull away and the speedo starts to bounce around, 40, 70, 120 allsorts, this must give the transmission mixed messages and the car does not know what gear it supposed to be in, or its like something has damp in it as I drive it for 15 to 30 mins and all of a sudden it clears and drives lovely again, so I found the post on here with ref to the ECU and sent away to america for the correct resistors and had them all replaced, car was then great for a few weeks, now its back, and its every time i leave the car standing for a day or so. I have now checked the wires in the boot hinge and all seems to be ok, I am at my witts end with it, has anybody had the same things go wrong for them as I cant find any of the same symptoms on the net or other forums, other things that happen are the radio lights are out but after 30 minutes or so they come on when lights are used and the ECT ( Ithink) light flashes not often but now and again. any ideas anybody please

Many thanks

Phil

 

[BachelorDays]

Intermittent electrical faults are the worst. The basics for me would be to check all the earth points. You've already checked the wiring around the ECU housing. How do the solder joints look on the ECU?

I'd also check the wiring around the alternator and put one of those volt meters in the cigarette lighter and see if you have steady voltage whilst driving.

I'd also examine the Battery connectors for loose wires/ corrosion.

Finally, I'd test voltage at the Battery when cranking cold. Could be low voltage in a start from cold causing an ECU glitch.

[Glider]

Hi thanks for your reply, i will check all what you said, but I have had a look at the wiring at the boot hinge and found that someone has been there before me as there are 2 x scotch locks attached to 2 wires, which I know from experience are a rubbish fix, one was connected to the white wire with the black line on it, which everbody goes on about so I took it off and found the white wire damaged, I wrapped some insulation tape around it, the other wire which was attached I just left hanging, I dont know what its for but everything seems to be working and it obviously isnt supposed to be there as it was scotch locked, not something many people would do, I have drove the car over the past three days and so far so good, but will see, I am getting an auto electrician friend to have a quick look at it for me whilst its all still appart to see if he can explain whats going on there and check around, I will update, thanks again 

 

Phil

  

 

 

 

[Connoisseur]

The white wire with black line on a Lexus is usually a ground/earth connector...........

hth

[BachelorDays]

Looks like you found the issue. Good idea to discuss with an auto electrician. Probably an old tracker installation crudely removed.

[steve2006]

If the ECT light is flashing I would get a diagnostic check performed to see if there are any stored fault codes which may help you locate the problem.

The speedometer is normally fed from one of the 2 speed sensors mounted on the transmission so it may also be worth checking the plug  connections and wiring to these also.

[MLW]

You could try an OBD2 check. Worked on my 430, but yours might be too old, i.e. not sure if you have a jack plug fitted. Mine is in front of the drivers right knee.

[Malc]

do you have a Mk2 last of,  or a first of the  Mk3 1995 car ?

Malc

[Glider]

On 3/22/2019 at 5:02 PM, Malc said:

do you have a Mk2 last of,  or a first of the  Mk3 1995 car ?

Malc

I think its a Mk 2 last of, as when I replaced the capacitors in the ECU there were supposed to be 6 caps 1994 supposed to be 8 caps, that also confused me as I found 9 in mine, 

Thanks Malc

Phil

[Glider]

On 3/22/2019 at 2:41 PM, MLW said:

You could try an OBD2 check. Worked on my 430, but yours might be too old, i.e. not sure if you have a jack plug fitted. Mine is in front of the drivers right knee.

To old it  just has OBD1, but thanks

[Glider]

On 3/20/2019 at 5:29 PM, steve2006 said:

If the ECT light is flashing I would get a diagnostic check performed to see if there are any stored fault codes which may help you locate the problem.

The speedometer is normally fed from one of the 2 speed sensors mounted on the transmission so it may also be worth checking the plug  connections and wiring to these also.

I have replaced the speed sensors and its OBD1 not 2

many thanks though

regards

phil

[Glider]

On 3/20/2019 at 12:01 PM, BachelorDays said:

Looks like you found the issue. Good idea to discuss with an auto electrician. Probably an old tracker installation crudely removed.

Your right, I found the problem ever since I took the scotch locks off its driven perfectly every day no problem at all, the 2 scotch locks provided a live and earth to after market reversing sensors which didnt work correctly anyway, this was sending signals to the ECU and confusing it. So my assumption of someone adding something to the vehicle was correct and this was confirmed by my auto electrician.

Thanks so much to everybody who tried to help,

kindest regards

Phil

[Glider]

On 3/19/2019 at 9:17 PM, Connoisseur said:

The white wire with black line on a Lexus is usually a ground/earth connector...........

hth

Great thanks

Phil