Won't start / electrical issue - Out of options, any advice welcome

[dignan]

I've got an incredibly odd and very frustrating problem that I've been dealing with for weeks, and any help or advice would be greatly appreciated. I had the truck(a '98 100 series with 150k miles - pretty much stock) towed to Toyota twice in the last four weeks because of a starting issue like many others here have had:

https://forum.ih8mud.com/100-series-cruisers/341011-cruiser-cranks-wont-start.html

https://forum.ih8mud.com/100-series-cruisers/179908-help-im-irate-ignition-trouble.html

https://forum.ih8mud.com/100-series-cruisers/402506-1999-uzj100-intermittently-drops-dead.html

Before the two towing sessions I replaced the fuel pump, all fuses related to ecu's, efi, etc. (although all tested fine) and double checked all relay and ecu connections but nothing made a difference. The immobilizer light would not go off when I inserted my key, the car would crank hard, but not start.

After the second tow to the dealership I talked with a tech about possible problem areas and I pointed out that when I bought the truck there was a very slight sunroof leak on the passenger side which I promptly fixed (it has been bone dry inside ever since). They visually inspected several of the connection points in the dash close to where they thought any moisture buildup might have occurred, and found that there was some corrosion on the connector that ties to the ABS computer. They told me the ABS system overrides the immobilizer as well as several other computer related starting systems and said that one of the wiring harness connectors should be replaced. They replaced the connector and told me it was ready to go and that I could pick it up anytime after paying the $350 charge.

I show up after hours to pick it up and it dies twice on the way out of the parking lot with almost every dash warning light flickering on and off the whole time. I leave it there that night and they call me two days later and tell me it's impossible to track down the "bad spot" in the wiring harness and the only way to solve the problem is to spend an additional $1650 to replace the entire front/main engine wiring harness (Toyota said they know it's a harness issue because there are no codes thrown each time they go to check).

I'm not sure what to do...money is definitely an issue. Should I buy a used harness and cut half of it and solder it to the half of the harness (passenger side dash) they suspect is bad? Do I just go ahead and replace the whole harness? Again, any help or advice would be greatly appreciated. Thanks for your time and help.

 

[agaisin]

I've got an incredibly odd and very frustrating problem that I've been dealing with for weeks, and any help or advice would be greatly appreciated. I had the truck(a '98 100 series with 150k miles - pretty much stock) towed to Toyota twice in the last four weeks because of a starting issue like many others here have had:

https://forum.ih8mud.com/100-series-cruisers/341011-cruiser-cranks-wont-start.html

https://forum.ih8mud.com/100-series-cruisers/179908-help-im-irate-ignition-trouble.html

https://forum.ih8mud.com/100-series-cruisers/402506-1999-uzj100-intermittently-drops-dead.html

Before the two towing sessions I replaced the fuel pump, all fuses related to ecu's, efi, etc. (although all tested fine) and double checked all relay and ecu connections but nothing made a difference. The immobilizer light would not go off when I inserted my key, the car would crank hard, but not start.

After the second tow to the dealership I talked with a tech about possible problem areas and I pointed out that when I bought the truck there was a very slight sunroof leak on the passenger side which I promptly fixed (it has been bone dry inside ever since). They visually inspected several of the connection points in the dash close to where they thought any moisture buildup might have occurred, and found that there was some corrosion on the connector that ties to the ABS computer. They told me the ABS system overrides the immobilizer as well as several other computer related starting systems and said that one of the wiring harness connectors should be replaced. They replaced the connector and told me it was ready to go and that I could pick it up anytime after paying the $350 charge.

I show up after hours to pick it up and it dies twice on the way out of the parking lot with almost every dash warning light flickering on and off the whole time. I leave it there that night and they call me two days later and tell me it's impossible to track down the "bad spot" in the wiring harness and the only way to solve the problem is to spend an additional $1650 to replace the entire front/main engine wiring harness (Toyota said they know it's a harness issue because there are no codes thrown each time they go to check).

I'm not sure what to do...money is definitely an issue. Should I buy a used harness and cut half of it and solder it to the half of the harness (passenger side dash) they suspect is bad? Do I just go ahead and replace the whole harness? Again, any help or advice would be greatly appreciated. Thanks for your time and help.

what happens if you spend the ~1600 and it doesn't solve the problem. are they gonna stand by their diagnosis? based on your description of events it seems like they're throwing parts at it instead of methodical diagnoses. if you have the skills and time would you try tracking down the electrical problems on your own? or is this your daily driver and you need it up and running as quickly and cheaply as possible?

if you dont have the time or interest etc to try yourself, I'd consider taking it to an independant toyota mechanic that is willing to truly diagnose the problem and pinpoint it. perhaps you can check the boards or ask around for a local shop, give em a ring and talk through the situation and history and see what kind of confidence they have and whether they'll stand by their diagnosis etc. fwiw a local indie shop by me will do up to 2 hours free diagnosis. he came through on an electrical issue i had - dealership would not take the time and wanted to replace the entire mfd, but he tracked it down to a short in the wiring.

 

[Trunk Monkey]

Start simple. Why is the key not disarming the immobilizer? Do you have a master key and have you tried to program a new one?

I would not splice half of the harness, you're just asking for connections problems down the road. I had a similar mystery problem with my ECU and it was very frustrating. And it's not impossible to track down the bad spot, it's just really labor intensive. There's a pile of junctions behind the dash. When I was working on my issue my friend, who's a Toyota Tech, did comment that there is a certain few blocks that are prone to corrosion because of either windshield problems or sunroof leaks.

 

[dignan]

what happens if you spend the ~1600 and it doesn't solve the problem. are they gonna stand by their diagnosis? based on your description of events it seems like they're throwing parts at it instead of methodical diagnoses. if you have the skills and time would you try tracking down the electrical problems on your own? or is this your daily driver and you need it up an running as quickly and cheaply as possible?

if you dont have the time or interest etc to try yourself, I'd consider taking it to an independant toyota mecahnic that is willing to truly diagnose the problem and pinpoint it. perhaps you can check the boards or ask around for a local shop, give em a ring and talk through the situation and history and see what kind of confidence they have and whether they'll stand by their diagnosis etc. fwiw a local indie shop by me will do up to 2 hours free diagnosis. he came through on an electrical issue i had - dealership would not take the time amd wanted to replace the entire mfd, but he tracked it down to a short in the wiring harness.

Great question, the service writer said they're certain that the new harness would do the trick and I didn't ask what if...I'll have him spell it out on Monday and see what he says. I can do some electrical work but this is definitely going to take a pro, I'd do it if I could just not sure what else to do.

I've never been to an indie shop that would do a free diagnosis but for sure worth the call around to find one, I've got AAA and a couple tows left on my account so I guess in theory I could move it around a couple times until I find someone who can take it on.

Thanks for your advice, it's really helpful to have some outside perspective.

 

[dignan]

Start simple. Why is the key not disarming the immobilizer? Do you have a master key and have you tried to program a new one?

I would not splice half of the harness, you're just asking for connections problems down the road. I had a similar mystery problem with my ECU and it was very frustrating. And it's not impossible to track down the bad spot, it's just really labor intensive. There's a pile of junctions behind the dash. When I was working on my issue my friend, who's a Toyota Tech, did comment that there is a certain few blocks that are prone to corrosion because of either windshield problems or sunroof leaks.

I have 5 keys...two remote keys, two regular keys, and one valet. This issue is bizarre either all of them work or none of them work.

Sorry to hear you had a similar problem, but good to know that ditching half the harness is not the way to go. Really appreciate you and Agaisin pitching in..you've given me some great things to sort through, I'll let you know what I find out.

 

[dignan]

I think I'm going to end up replacing the harness with a used one and have it done at Toyota for about half of the original price they quoted me. The used harness is in great shape (tests as new) and should work perfect. I say I think because I was warned by the service advisor (who incidentally has been the best of any Toyota rep I've worked with) that I should sell this truck immediately because in his experience these electoral issues would show up elsewhere. Is there much validity to what he's saying? Anyone else have experience chasing down these kinds of issues?