Manager Forum

1GNDT13W21K223538 - this blazer came in with intake leaking coolant.

Replaced gaskets and distributor making noise replaced whole distrbutor. Test drove, went good. customer took over weekend and brought back on monday saying tach jumping up and down over 2000 rpm. code was stored for crack sensor circuit A. replaced sensor, same code. all wiring checks & ohms ok have signal 2 pcm. installed used pcm had programed still no change, same code. even have ran seperate wires for crank sensor eliminating wire harness to no avail. had old distrib. reinstalled reaching for straws; same outcome.

took to dealership, they had for a week with no luck either.

did check reluchter wheel on crank shaft could not seem to get play out of it also had lab scope hooked to sensor right at sensor wires did have glitch once and awhile. we were using OE sensor so thought nothing of needing shim under sensor like some post say on the repair side of mitchell went out on a lim and installed a A/C compressor seal work like a champ yee ha

Well, first of all, I.d be checking the reluctor wheel on the crankshaft to make sure there is no issues with it. Then, if that is ok, I'd be hooking up my lab scope to the crank sensor signal wire and monitoring it.

Also, check the crankshaft for end play. A badly worn crankshaft thrust bearing can set this code by allowing the reluctor wheel to intermittantly slip beyond the ability of the sensor to pickup.

could be an unrelated issue and just bad timing. on occasion i've had vehicles come in after i've worked on them with other issues. however, on this on i would look long and hard at all harness connections especially grounds. a bad ground will cause a spike just like a surge would. also on older vehicles i see ( a lot) wires breaking in the harness where it bends when i move it out of the way.