awilson97

Hi all -

I've been experiencing some trouble with my '97 Silverado's 4L60E as of recently. Transmission went out at 265k miles (destroyed clutch packs) about a year and a half ago. Had it rebuilt by a local guy who did a great job. Didn't have any problems at all for about a year. About 10k miles later, transmission starts slipping. The weird thing is that it only slips when warm. Perfect shifts into 2nd - OD... for about 5 minutes of driving. Then it struggles to shift. About half the time, it eventually will, but not without some hesitation accompanied by a hard shift into gear. Had all the symptoms of a bad torque converter (fluid levels were fine). Replaced the torque converter which did nothing. Same exact issue. (Although did have to drain the fluid from the transmission and found no apparent signs of clutch failure, e.g., no burnt-smelling fluid, no metal chunks/shards, etc.)

I'm getting a hunch it's something electrical, so I hook up my OBD scanner to check for codes... can't communicate with the vehicle. I check all the fuses (including cigarette lighter), replace one blown one, still can't communicate. (Also tried the scanner on another car and it worked fine, so it's not the scanner.)

I also noticed that the CEL doesn't come on. It used to be on all the time, but now, it never shows up (doesn't even come on at startup). Is this a problem with my computer? Could the shifting problems also be related to this?

Where should I even start trying to troubleshoot this problem? I'm assuming I need to get the OBD working again first. Any thoughts? I'm overwhelmed, lol. Any help would be appreciated.

Thanks!

Rednucleus

If rebuilt by a great guy 1.5 yrs ago, I would start by talking with him. Any warranty on his work? Esp if trouble at 10k I would hope he could help you out.

awilson97

The trouble is he wasn't really working with a shop at the time. I've called him about it and described everything to him but he is equally at a loss. I'm happy to pay him to come diagnose it in-person, but he hasn't had any time to do so and doesn't know when he will, as he's working with a shop again.

I'm hoping to at least diagnose the issue before bringing it in anywhere.

meternerd

If your CEL doesn't ever come on, it could be a burned out bulb, but a failure to connect sounds like a computer problem. I'd try to get the comm port working first so you can check for codes, then move on to the tranny....they might just be related. ECM might have a problem, so trying a replacement would be the next logical step. Wrecking yard? Used ones are also available online.

awilson97

Thanks for your reply! Tested the bulb and it was fine. Went to my local salvage yards and only found near matches... thought I'd read somewhere that the ECM has to be an exact match to make flashing easier (or possible, lol). Will search around online.