1997 Chevy Blazer 4WD Won't Engage

CHEVROLET
Avatar
DOUGHSP
  • MEMBER
  • 1 POST
1997 Chevy Blazer 148,000 miles. My front wheels will not engage in 4hi or 4lo. The front drive shaft will engage and the vacuum actuator moves but is sticky and does not move smoothly. The front diff was low on fluid so I drained and refilled. My first guess wold be the actuator. What does the switch on the front diff do? Also, 90% of the time all lights (head, interior, dash, fuel gage movement) pulsate. It gets worse with increase of RPM. It has done this for years. Could it be the voltage regulator?
Dec 18, 2006 at 10:01 PM
Advertisement
Avatar
2CARPRO JACK
  • ✓Experienced Mechanic
  • 11,533 POSTS
Could be the voltage reg.Check all ground and power wires for good clean connections.The 4x4 problem is the actuator.GM had alot of problems with it especially in cold weather.The updated oart has an integral heater in it.They are easy to install and wire.
Dec 18, 2006 at 11:37 PM
Avatar
JSTEINDL
  • MEMBER
  • 10 POSTS
I agree with the acctuator being your 4x4 problem. As for the pulsating of your lights etc, have your alternator checked. My 98 silverado did the same thing. Had a bad alternator. Another common problem in GM's.
Dec 21, 2006 at 8:09 PM
Avatar
DOPEY
  • MEMBER
  • 4 POSTS
[quote:1b8bd1085d="jsteindl"]I agree with the acctuator being your 4x4 problem.[/quote:1b8bd1085d]

I replaced my accuator, but it always stays depressed unless I disconnect the vacuum line. And it doesn't go all the way into the 4x4 just makes a mild clanking like its just barely in 4x4

I don't know what controls the vacuum. I tried pulling on the cable and I can't pull it far enough to engage the 4x4 either?

any advice?

TIA
Oct 31, 2007 at 1:34 PM
Avatar
DOPEY
  • MEMBER
  • 4 POSTS
[quote:ece86527b0="dopey"][quote:ece86527b0="jsteindl"]I agree with the acctuator being your 4x4 problem.[/quote:ece86527b0]

I replaced my accuator, but it always stays depressed unless I disconnect the vacuum line. And it doesn't go all the way into the 4x4 just makes a mild clanking like its just barely in 4x4

[update] I had to replace the vacuum switch on the transfer case, now the acuator works fine.

I don't know what controls the vacuum. I tried pulling on the cable and I can't pull it far enough to engage the 4x4 either?

any advice?

TIA[/quote:ece86527b0]

[update]
I have a 1996 Blazer 4x4 with manual shift 4x4 (not dash button) my differential is not engaging as it should.

The vacuum acuator was bad, replaced. The vacuum switch was bad, replaced. The cable may have been bad, replaced.

I took the cable off at the housing on the differential and removed the housing face plate. I used a pair of vise grips to pull the acuator out to engage the 4x4 but all it would do is grind mildly, all it would do is grind mildly when I had it all
connected too.

So I have traced the problem to the differential. I cant seem to engage the "collar" for the axles to engage.

I just don't know what to do from there? any ideas would be appreciated.

TIA it's appreciated.
Nov 1, 2007 at 12:04 PM
🔧 Tools & Auto Repair Parts
Find automotive tools, diagnostic equipment, and replacement parts for your next repair.
Shop on Amazon →
Paid affiliate link. As an Amazon Associate, we earn from qualifying purchases.

Suggested Repair

Replace the sticky front axle vacuum actuator with the updated heated unit. For lights and gauges that pulsate with RPM, check grounds and power connections and test the alternator and voltage regulator.

Conversation Summary

A 1997 Chevrolet Blazer owner said the front wheels would not engage in 4-high or 4-low, although the front driveshaft engaged and the vacuum actuator moved stickily. The front differential had been low on fluid and was refilled. Experts identified the actuator as the common four-wheel-drive fault and advised checking grounds, power connections, the voltage regulator, and alternator for the pulsating lights. Later posts about a similar 1996 Blazer said the actuator, transfer-case vacuum switch, and cable were replaced, with grinding still traced to the differential collar, but no further expert repair was given.

Related Repair Questions

Add a reply
Join 2CarPros for free, one of the most advanced car repair communities on the internet. From first-time drivers to seasoned mechanics, everyone is welcome to reply, share details, and get better answers. You can add a temporary image or video first; uploads are limited to 20 MB.

Ask a new question

Frequently Asked Problems for This Vehicle